Heat olive oil in large skillet over medium-high heat.
Brown ground beef thoroughly, breaking apart with spatula.
Add diced peppers and cook 5 minutes until softened.
Boil rotini pasta according to package directions until al dente.
Drain pasta and place in greased 9x13 baking dish.
Pour heavy cream over pasta and stir to coat evenly.
Layer meat mixture over pasta, then spoon marinara sauce on top.
Sprinkle mozzarella cheese evenly over entire surface.
Bake at 375°F for 25 minutes until golden and bubbly.
Rest 5 minutes before serving.
Tip: Do not overcook pasta initially as it continues cooking during baking.
Tip: Use freshly shredded mozzarella for best melting and stretching results.