Step 1

Heat a large skillet over medium-high heat. Cook and stir ground beef and onion in the hot skillet until beef is browned and crumbly, 5 to 7 minutes. Drain and discard grease.

Step 2

Stir mushrooms, tomato sauce, olives, and garlic into the skillet. Crush stewed tomatoes into smaller pieces and add to the mixture. Season with salt and white pepper. Let simmer, uncovered, until liquid reduces, 20 to 30 minutes.

Step 3

Slice zucchini lengthwise; cut into 1/2-inch slices and add to the skillet. Cook, covered, until firm yet tender to the bite, 5 to 7 minutes. Stir in Cheddar cheese and cook, covered, until melted, 3 to 4 minutes. Serve.