1. Preheat oven to 350°F. Warm oil in a large skillet over medium-high heat. Add meat mix, chili powder and bell pepper; cook, stirring, until beef is browned, about 6 minutes. Stir in adobo and tomato sauce and bring to a simmer. Reduce heat to medium-low; simmer for 3 minutes.
2. Mist a 9-by-13-inch pan with cooking spray. Slice both rolls of polenta into 1/8-inch rounds, about 30 pieces total. Line bottom of pan with half of polenta, overlapping if needed.
3. Spread meat mixture evenly over polenta and sprinkle with 1 cup cheese. Arrange remaining polenta on top; sprinkle with remaining cheese. Cover with foil and bake until bubbling, 25 to 30 minutes.