Mesquite and Cactus Cornbread

3/4 cup chopped nopalitos (about 2 medium prickly pear pads, available in the produce section of many large grocery stores)
pinch baking soda
1 cup mesquite flour (make your own by drying and grinding mesquite bean pods, or purchase online or in Southwestern specialty shops)
1 cup yellow cornmeal
4 teaspoons baking powder
1/4 teaspoon salt
1 cup butter, melted
1 cup sugar
4 eggs
3/4 cup corn kernals (fresh, canned, or frozen)
1/2 cup shredded Monterey Jack cheese
1/2 cup shredded Cheddar cheese

Preheat oven to 325 degrees. Grease and flour a 9x13 inch baking dish. Cook chopped nopalitos in boiling water with a pinch of baking soda until they turn a dull green (3-4 minutes). Drain. In a large bowl, beat together butter and sugar. Beat in eggs one at a time. Blend in nopalitos, corn, and cheeses. In a separate bowl, stir together mesquite flour, cornmeal, baking powder and salt. Add flour mixture to nopalito mixture; stir until smooth. Pour batter into prepared pan. Bake 1 hour, until the top is golden brown and a wooden pick inserted into center comes out clean.