1. Soak sun-dried tomatoes. Lightly sweat leeks and reserve to cool. Cook bacon until desired doneness, drain, chop and reserve. While leeks & bacon are cooking, bring water to a boil to cook your pasta.
2. Cook pasta, drain, rinse & reserve. While pasta cooks, drain and chop sun-dried tomatoes, then prepare your sauce.
3. In a medium saucepan, melt butter over medium heat, whisk in four until blended and continue to cook for three or four minutes until your roux is cooked. Add milk and whisk, over medium heat until smooth. Deduce heat, and bring to a low simmer for about ten minutes before adding 2 1/2 cups of cheese, a handful at a time, stirring as you go. Finally, add nutmeg and season with salt and pepper to taste.
4. Pre-heat oven to 350°F (175°C). Coat an 8 x 8 (3 quart) casserole dish, or 6 large ramekins, with non-stick spray and reserve. In a large bowl, mix the pasta with sun-dried tomatoes, leeks, roasted garlic, and bacon. Add mornay sauce until desired sauce to pasta mixture is achieved, taste, adjust seasoning if needed, then scoop into your chosen dish for baking. Top with remaining cheese.
5. Bake, uncovered: 20 – 25 minutes for individual ramekin dishes or 45 – 50 minutes for a deep dish 8 x 8 casserole size; until bubbling and hot with a crispy, melted cheese layer on top. Remove from oven and serve piping hot.