#1 Onion sauce: In a saucepan add 2 tablespoons butter, onion and bay leaf saute for 5 minutes. Add apple and white vinegar, season with pepper. Reduce almost completely #2 Add remaining butter, cream, and cheese to the resulting onions. Heat and blend well using an immersion blender (hand blender) #3 Cook pasta according to package directions and drain. Toss pasta briefly in the onion cream and plate without piling up the penne #4 Finish with a few thyme leaves and, if you like, a few pieces of onion cooked in the vinegar for a few minutes, as shown in the photo.