Finely chop the onion and press the garlic or chop it very finely.

Wash the basil leaves and put them in a mortar. Pound or grind them until the essential oils are released and you have a paste. Leave a few leaves for decoration.

Heat some butter in a pot and sauté the chopped onion until translucent. Add the garlic and sauté briefly until fragrant.

Add the remaining butter and let it melt. Then stir in the flour and cook, stirring constantly, for about 1-2 minutes to get a light roux.

Slowly pour the milk into the roux, stirring constantly with a whisk to avoid lumps. Bring the sauce to a boil while stirring and simmer for about 5 minutes until it thickens.

Stir the pounded basil paste, vegetable broth powder, salt, pepper, and a pinch of grated nutmeg into the sauce. Taste the sauce and season further if needed.

Cook the tortelloni according to package instructions in plenty of salted water until al dente.

Drain the tortelloni and let them drip briefly.

Add the cooked tortelloni directly to the basil sauce in the pot and gently mix everything together so that the tortelloni are well coated with sauce.

Serve the tortelloni with basil sauce on plates. Tear the buffalo mozzarella and distribute it over the tortelloni.

Decorate the dish with the remaining fresh basil leaves and enjoy it immediately.