Melt butter over medium heat in skillet. Add garlic and cook until fragrant but still firm, about one minute. Add onion and cook and stir for one minute. Add crawfish meat and cook until opaque in color, about 1-2 minutes. Do not overcook. Add cooked pasta, wine, salt, pepper and crushed red pepper (if using...I used it and it was a great kick) and stir till combined. Garnish with grated parmigiano reggiano (if using...I did not). ENJOY!