Preheat the oven to 350 degrees. Lightly grease an 8×8 casserole dish or baking pan.
In a large bowl, beat the eggs. Stir in the flour, dry mustard, baking powder and salt. Stir in the cottage cheese, Monterey Jack cheese, cheddar cheese, butter and jalapeños, and mix until incorporated.
Pour the eggs into the casserole dish, and bake for 20-25 minutes or until the top is lightly browned and the center is firm. Serve warm with salsa.