Warm Penne Pasta Salad

Ingredients
- Salt
- 1 pound penne pasta
- 4 tablespoons butter
- 2 cloves garlic, finely chopped
- 1 small onion or 1 large shallot, finely chopped
- 2 cups frozen peas, defrosted
- Salt and pepper
- 1 1/2 cups fresh ricotta cheese
- 4 tablespoons thyme, finely chopped
- 1/2 cup grated Parmigiano Reggiano cheese (a couple of handfuls)