In a medium saucepan, melt the butter over medium heat. Once the butter is melted, add the flour (combined with seasoning - salt, white pepper, onion powder) and stir until a paste is formed. Add the heavy cream and stir until the mixture is smooth.
Add the cubed cream cheese, stirring into the sauce mixture until mostly melted. Add the lobster stock and warm the sauce up, enough to finish melting the cream cheese.
Add the chopped white cheddar curds and stir until mostly melted. Then add the chopped smoked white cheddar and stir until melted as well.
Pour the cheese sauce over the cooked macaroni noodles, and stir to coat all of the pasta. Add the diced lobster meat and gently stir into your stove top macaroni and cheese. Garnish with additional chunks of lobster meat and fresh dill sprigs, if desired. Serve immediately.