Preheat the oven to 400℉.
Cook the pasta in a large pot of salted water, but remove it 1 minute before it reaches al dente. Reserve 1 1/4 cup of pasta water before draining.
While the pasta is cooking, melt the butter in a deep skillet or braiser over medium-low heat. Once melted, add the spices (garlic powder, onion powder, both paprikas, and cayenne) and bloom them for 1 minute, stirring constantly to prevent burning.
Add the flour and cook for 2–3 minutes, stirring every 20–30 seconds.
Pour in the half-and-half and whisk vigorously to combine.
Add the cream cheese and minced pimento peppers. Salt to taste. Raise the heat to medium and bring the sauce to a simmer, cooking for 1-2 minutes or until the cream cheese is incorporated and the sauce thickens enough to coat the back of a spoon.
Stir in 1 cup of the reserved hot pasta water.
Remove the sauce from the heat, then add the cheese gradually, stirring until each addition melts before adding more.
Once the cheese sauce is smooth and melted, toss in the pasta and the additional 1/4 cup of pasta water and stir to combine.
If working with an oven safe pan crumble the crackers over the top of the mac and cheese. If moving the mac and cheese to an oven safe dish, transfer then add the cracker topping.
Bake for 5-7 minutes, until the cracker topping is a bit more golden brown. Remove and serve.