In a small saucepan, whisk together the cornstarch, brown sugar, pineapple with its juices, salt, and cayenne pepper until combined.
Cook over low heat and allow the sauce to come to a gentle boil. Whisk in the honey mustard. Simmer for 5 to 10 minutes, until the sauce is thickened and homogenous. Remove from the heat and keep warm.
Carrot Cake
Preheat the oven to 350 degrees F (175 degrees C). Grease an 8- by 8-inch baking pan with non-stick spray oil.
In a large bowl, mix the oil, sour cream, brown sugar, and molasses together. Mix in the eggs, one at a time. Fold in the grated carrots.
In a separate bowl, whisk together the flour, cinnamon, baking soda, nutmeg, salt, and cloves. Add the dry ingredients to the wet ingredients and mix until just combined. Fold in the ginger, if using.
Pour the batter into the prepared baking pan. Bake until a toothpick inserted into the center of the cake comes out clean, 45 to 55 minutes.
Cut the cake into squares and serve with the pineapple sauce and whipped cream on top of each square.