Preheat oven to 400 degrees F
.
Bring a pot of water to a boil and salt generously
.
While the water comes up to a boil, cook the bacon in large skillet until crisp.
Remove the bacon and add additional butter if needed to the skillet.
When the butter melts completely, add the garlic and cook until fragrant.
Add the all-purpose flour and cook over medium-high heat for 2-3 minutes.
Add the milk and whisk to remove any lumps
.
Cook over medium-high heat until the sauce thickens
.
While the sauce is thickening cook the macaroni according to packaging instructions.
Once the sauce thickens, turn off the heat and stir in 3/4's of the cheddar and gouda, leaving some behind for later
.
Season the cheese sauce with salt and pepper.
In a small bowl, combine the breadcrumbs and melted butter.
When the pasta is almost done cooking, drain it, and add it to the cheese sauce.
Place the macaroni and cheese sauce in a casserole dish and stir in the sour cream. Top it off with the buttered breadcrumbs and remaining cheese.
Bake for 20 minutes or until nice and crispy.
Add the finely chopped cooked bacon and scallions.