Preheat the oven to 375 degrees F (190 degrees C).
Heat a large skillet over medium-high heat. Cook and stir ground beef and sausage in the hot skillet until browned and crumbly, 5 to 7 minutes. Drain and discard grease. Add onion, tomato paste, garlic, parsley, basil, oregano, salt, and pepper. Let simmer, uncovered, for 5 minutes.
Combine cottage cheese, Parmesan cheese, and egg in a bowl for filling.
Unroll 1 can of crescent rolls on an ungreased 15×13-inch cookie sheet and press the edges together to seal. Spread 1/2 of the meat mixture on top, to within 1 inch of the edge of the dough. Top with cheese filling. Spoon remaining meat mixture carefully on top. Place mozzarella cheese slices on top of the meat.
Unroll remaining crescent can and place dough on top, being careful to overlap the edges by about 1/4 inch. Pinch the edges to seal to prevent leaking. Brush dough with milk; sprinkle on sesame seeds.
Bake in the preheated oven until golden, 20 to 25 minutes.