In a large, heavy, ovenproof skillet over medium-high heat, heat the oil. Add the bell pepper, onion and mushrooms and cook until softened, about 8-10 minutes. Season with salt and pepper.
Add the tomato paste and cook for a minute or two until fragrant. Add the turkey and chili powder and cook, breaking up the turkey, until the turkey is browned and cooked, about 3-5 minutes. Add the tomatoes (undrained) and cook until some of the liquid has evaporated, about 3 minutes. Season with salt and pepper, then remove from the heat.
Meanwhile, in a bowl, whisk together the flour, baking powder, baking soda and salt. Cut the butter into the flour mixture using a pastry cutter or a fork. Stir in the buttermilk and the cheese just until moistened. Divide the mixture into 9 equal pieces and form into 9 biscuits. Place over the turkey mixture.
Bake in the preheated oven until the biscuits are golden brown, about 20 minutes.
Notes
*I only used 1/2 tablespoon chili powder since I was feeding my family, and it was still very mild.slightly adapted from One Pot