Cook pasta according to package instructions.
While pasta is cooking, mash together the softened butter, roasted garlic, parsley, and parmesan in a large bowl.
Once pasta is finished cooking, use a slotted spoon (or tongs) to immediately add the hot pasta into the butter mixture — you want to get a little bit of pasta water in the bowl too!
Toss, season to taste with salt and pepper, and serve.