Pumpkin Spice Caramels in the microwave with a dose of "science"

   Candy is made when crystals separate from a solution and science is definitely a part of the process. It begins with a supersaturated solution (a high percentage of sugar). During the heating process crystallization occurs -- the goal is small crystals that grow rapidly. The addition of corn syrup to a recipe and stirring assist in this process, as do the correct concentration of ingredients and controlled temperature. Ideal temperatures vary based on the type of candy: fudge - 234-240°F; caramels - 242 - 248°F, and so on.  Before the use of candy thermometers, cooks checked the donnas of candy by dropping the mixture into cold water. If a soft ball formed, the fudge had cooked the optimum time; a firm ball meant caramels should be removed from the heat.
Barry's caramel recipe provides precise ingredients and instruction for cooking on top the stove and monitoring the temp with a candy thermometer.
Despite the fact that I understand the science involved in candy making and the need for precise measurement and controlled temperature, I was intrigued with the idea of making caramels in the microwave and even more intrigued with the addition of pumpkin and pumpkin spices to the mix.
The recipe I used was from Butter with a Slice of Bread blog and yielded a very nice product but not without problems! The recipe instructs to use a large glass bowl so I began with an 8-cup capacity Pyrex® measuring pitcher. Halfway through the second 6-minute heating interval, the candy solution was overflowing the container. After cleaning up the mess and rescuing as much as I could, I transferred the solution to a 12 to 14 cup capacity pottery bowl—that took care of one problem.
Candy instructions on the blog are written for a 1000 watt microwave and it clearly states  adjustments may need to be made depending on the wattage of your own microwave (I found the wattage in the microwave's manual). Mine was also 1000 watts so I proceeded with the 4-part heating instructions as listed: 6 minutes, 6 minutes, 5 minutes, 5 minutes. All went well expect for the last 5 minute segment -- when I removed the bowl, the caramels were very brown on the edges and I knew that they had gone from the firm ball stage (ideal for caramels) to the perimeter of the hard ball stage. I went ahead and continued with the recipe and they were edible and really quite tasty but definitely very chewy. 
My solution: Monitor the temperature of the candy as it is heating in the microwave and stop cooking before the temperature goes above 248°F. The result: A caramel that is both easy and successful (soft & flavorful) when scientific principles are applied.
Note: This recipe could also be made the traditional way by  cooking on top of the stove.

Pumpkin Spice Caramels
1/2 cup (1 stick) butter
1 1/2 cups granulated sugar
1 cup corn syrup
1 (14 oz.) can sweetened condensed milk or make a homemade version
1/2 cup pumpkin puree (if using pumpkin pie filling make sure it does not contain added sugar and spices)
1 teaspoon pumpkin pie spice (or make your own: scant 1/2 tsp. cinnamon, scant 1/4 tsp. ginger and allspice + 1/8 tsp. nutmeg)

1. Prepare a  7 x 11" baking dish or pan by lining with foil or parchment and spraying with non-stick spray. (9×13" can be used at well, or for thicker caramels, use an 8×8").  
   
       
2. Melt butter in a large microwave safe bowl --- at least 12 to 14 cup capacity.           
3. Add all other ingredients and stir to combine.
   
   
   
   
4. Microwave mixture in 4 intervals, quickly stirring after each interval and returning to the microwave. Begin to monitor temperature of solution with a candy thermometer during the 3rd and 4th heating -- do not let temp go past 248°F!  1st heating: 6 minutes; 2nd heating: 6 minutes; 3rd heating: 5 minutes; 4th heating: just until temperature register 248° (5 minutes or less).     

   

   After 2nd 6 minutes of heating.

   

   After 3rd 5 minutes of cooking.

   

                                              After last heating.                                                                                                                                                                                                                                                                                                                                                                                            

5. Stir caramel once more then pour into prepared pan.  
   
6. Cool until set; if you’re in a hurry, you can place the pan in the fridge for about 2 hours. Otherwise it will set up nicely just resting in room temperature for several hours.   
7. Remove from pan and slice into strips with a large knife or kitchen scissors.  
   
8. Cut into small squares and wrap in wax paper, twisting the ends to seal.  

Recipe without photos . . .
Pumpkin Spice Caramels

1/2 cup (1 stick) butter
1 1/2 cups granulated sugar
1 cup corn syrup
1 (14 oz.) can sweetened condensed milk or make a homemade version
1/2 cup pumpkin puree (if using pumpkin pie filling make sure it does not contain added sugar and spices)
1 teaspoon pumpkin pie spice (or make your own: scant 1/2 tsp. cinnamon, scant 1/4 tsp. ginger and allspice + 1/8 tsp. nutmeg)

1. Prepare a  7 x 11" baking dish or pan by lining with foil or parchment and spraying with non-stick spray. (9×13" can be used at well, or for thicker caramels, use an 8×8").       
2. Melt butter in a large microwave safe bowl --- at least 12 to 14 cup capacity.           
3. Add all other ingredients and stir to combine.
4. Microwave mixture in 4 intervals, quickly stirring after each interval and returning to the microwave. Begin to monitor temperature of solution with a candy thermometer during the 3rd and 4th heating -- do not let temp go past 248°F!  1st heating: 6 minutes; 2nd heating: 6 minutes; 3rd heating: 5 minutes; 4th heating: just until temperature register 248° (5 minutes or less)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
5. Stir caramel once more then pour into prepared pan.  
6. Cool until set; if you’re in a hurry, you can place the pan in the fridge for about 2 hours. Otherwise it will set up nicely just resting in room temperature for several hours.   
7. Remove from pan and slice into strips with a large knife or kitchen scissors.  
8. Cut into small squares and wrap in wax paper, twisting the ends to seal.