Set oven to broil at level 1 (about 500 degrees). Line a baking sheet with foil and coat with cooking spray.
Spread polenta slices on prepared baking sheet and coat tops with cooking spray or drizzle with oil. Broil for 5 to 7 minutes, flip and broil another 5 minutes until starting to brown on outside.
Serve polenta cakes with vegetarian bolognese on top and sprinkle with Parmesan (or nutritional yeast, if vegan).
The longer you simmer the sauce, the deeper and richer the flavor becomes.
*You can use freshly prepared lentils, canned lentils, or packaged steamed lentils, which can be found in the produce aisle of some supermarkets.