Preparation

• Melt the butter in a 10-inch Dutch oven over medium heat. Add the crushed crackers, black pepper, and kosher salt. Stir to coat with the melted butter. Toast until golden brown, 2 to 4 minutes. Transfer to a plate to cool and wipe the pot clean.
• In the same pot, melt the butter over medium heat. Once melted, add the ground mustard, pepper, and cayenne (if using). Stir to combine, lightly toast until fragrant, 15 to 30 seconds. Do not let it brown.
• Add the water, half and half, and kosher salt to the butter mixture. Stir to combine and bring to a boil over high heat, uncovered.
• Once boiling, stir in the elbow macaroni, adjusting the heat to maintain a rolling boil. Continue to cook uncovered, stirring every minute, until the pasta is tender and the liquid is reduced enough to reveal the top layer of elbows, 6 to 9 minutes. Remove from heat.
• Add the cream cheese to the pasta mixture and stir until almost completely melted. Add the cheddar and Monterey Jack, stirring until completely melted and saucy.
• Taste and season with more salt and pepper as needed. Serve immediately topped with toasted Ritz topping, if using.