Preheat oven to 350 degrees F. Coat 15 standard muffin cups with cooking spray.
Place a piece of butter and a scant 1/2 tsp. maple syrup in the bottom of each muffin cup. Use a 2 1/2-inch cookie cutter to trim pear slices into 15 rounds. (Keep the seeds in to prevent batter from seeping through.) Place 1 round in each cup.
Whisk flour, baking powder, ginger, cinnamon, nutmeg, salt, and cloves in a medium bowl.
Whisk brown sugar, boiling water, molasses, and baking soda in a large bowl until foamy. Whisk in eggs and oil. Add the flour mixture in 3 additions, whisking after each until incorporated.
Divide the batter among the muffin cups, using about 1/4 cup batter for each. Bake until a toothpick inserted in the center comes out clean, 18 to 22 minutes.
Let the cakes cool in the pans for 5 minutes. Run an offset spatula around the edges, place a wire rack on top of the pans, and invert to unmold them. Garnish with cinnamon, if desired.
Sugar Substitute: We do not recommend one for this recipe.
Equipment: 2 standard muffin tins, 2 1/2-inch cookie cutter