In a large pot over medium heat, melt the butter.

Once the butter is melted add the flour and quickly whisk to incorporate the flour into the melted butter being careful not to let the butter burn.

Cook the flour and butter together for about a minute.

Add the milk and half and half.

Whisk until the mixture starts to bubble and thicken.

Reduce the heat to low and add the salt, pepper, mustard and chicken bouillon cube.

Add the cheeses and stir until they are melted.

Keep the cheese sauce warm while you cook and drain the pasta.

Add the pasta to the cheese sauce and stir to combine.

Serve immediately.