Preheat your oven to 400°F (200°C).

Bring a large pot of salted water to a boil and add the dry elbow macaroni, cooking according to package instructions until just tender, about 7-8 minutes. Drain the pasta and return it to the pot.

In the same pot, over medium heat, combine the cooked macaroni with gruyere, sharp cheddar, white cheddar, and heavy cream. Stir constantly for about 5 minutes until the cheeses are fully melted.

Season the mixture with salt and black pepper to taste.

Prepare your bell peppers by chopping off the tops and scooping out the seeds and membranes.

Fill each prepared bell pepper with the macaroni and cheese mixture, packing it snugly.

Place the stuffed peppers upright in the baking dish and bake in the preheated oven for 10-15 minutes, or until the cheese is melted and bubbly.

Let the peppers cool for a few minutes, garnish with freshly chopped parsley, and serve warm.