Instructions
Make the Mac and Cheese Filling: 1. Fill a medium saucepan with water. Add a generous amount of salt; the water should taste like seawater. Bring the salted water to a boil. 2. Add the 8 ounces of macaroni to the boiling water. Stir occasionally. Cook the macaroni until it is al dente, which means tender but still slightly chewy. This usually takes 8 to 10 minutes, or follow the package directions. 3. While the pasta cooks, mix the dry ingredients. In a small bowl, whisk together 1/3 cup plain flour, 0.75 teaspoon mustard powder, 0.5 teaspoon garlic powder, 0.5 teaspoon kosher salt, 0.5 teaspoon black pepper, and 0.125 teaspoon cayenne pepper. Set aside. 4. Drain the cooked macaroni using a colander. Do not wash the pasta pan. 5. Place the empty pasta pan over low heat. Add 6 tablespoons of butter to the pan. 6. Once the butter has melted, add the flour mixture from step 3 to the pan. Whisk constantly. Cook for about 1 minute until the mixture begins to brown and smells nutty. Watch carefully to prevent scorching. 7. Slowly pour 1.5 cups of whole milk and 1 cup of heavy cream into the pan with the flour mixture. Whisk constantly until everything is well combined. 8. Continue to whisk and cook the sauce for about 2 minutes, until it is heated through and just starts to thicken. Remove the pan from the heat. 9. Gradually add 1 pound of Monterey Jack cheese to the sauce. Stir constantly with a wooden spoon or silicone spatula until all the cheese has melted into a smooth sauce. 10. Add the drained cooked macaroni to the cheese sauce. Stir to combine thoroughly. 11. Prepare a 9-by-13-inch (23-by-33-centimeter) baking sheet with a rim. Line it with parchment paper or aluminum foil. Lightly coat the paper or foil with nonstick cooking spray or butter. 12. Pour the warm mac and cheese onto the prepared baking sheet. Use a spatula to spread it evenly. 13. Take another piece of parchment paper. Coat one side with cooking spray or butter. Place this paper, coated side down, directly on top of the mac and cheese. 14. Refrigerate the mac and cheese until it is cool and firm. This will take about 1 hour. Make the Grilled Cheese Sandwiches: 15. Prepare the garlic butter. In a small bowl, combine 4 tablespoons of butter with 1 teaspoon of garlic powder. Stir until well blended. 16. Remove the firm mac and cheese from the refrigerator. Carefully peel off the top layer of parchment paper. 17. Use a knife to cut the mac and cheese into 8 equal pieces. Each piece will be one grilled mac and cheese sandwich filling. (You can store individual portions in plastic bags in the refrigerator for up to 3 days, or freeze them for up to 1 month.) 18. Heat a large cast-iron or nonstick skillet over medium-low heat. 19. Spread about 3/4 teaspoon of the garlic butter on one side of each of the 16 bread slices. 20. Arrange 8 bread slices, buttered-side down, on a clean cutting board. 21. Place one slice of Cheddar cheese on top of each of these 8 bread slices. 22. Carefully transfer one piece of mac and cheese onto each Cheddar slice. You can slide your hand or a spatula under the mac and cheese piece to move it. 23. Place one slice of Colby Jack cheese on top of each mac and cheese piece. 24. Cover with the remaining 8 bread slices, buttered-side up. 25. Place as many sandwiches as will fit into the heated skillet without crowding. Cover the skillet. 26. Cook for about 4 minutes until the bottoms of the sandwiches are nicely browned. 27. Flip the sandwiches over. Cook for another 4 minutes until the second sides are browned, both cheeses are melted, and the mac and cheese filling is heated through. 28. Repeat steps 25-27 with any remaining sandwiches. 29. Cut the cooked sandwiches in half diagonally, if desired. Serve immediately.