Preheat the oven to 350°F. Line a 9x13 baking dish with parchment paper or aluminum foil.

In a medium saucepan, melt 4 tablespoons of butter over medium heat.

Add the flour, about 1⁄2 teaspoon each of salt and pepper, ground mustard, and nutmeg. Cook, stirring with a spatula, until a paste forms and begins to brown.

Drizzle milk in, one tablespoon at a time, whisking mixture constantly. When all the milk has been added, the white sauce should be smooth.

Bring sauce to a low boil, stirring constantly, until it thickens. Remove from heat.

Add grated cheese to the sauce and whisk until completely melted and smooth. Set sauce aside.

Slice the full sheet of Hawaiian rolls in half and set the top section aside. Place bottoms of rolls into prepared baking dish.

Cover the roll bottoms with 2-3 layers of sliced turkey breast.

Top the turkey breast layer with tomato slices. Sprinkle with salt and pepper.

Liberally spoon the cheese sauce over the tomato layer.

Top cheese sauce with a thick layer of bacon and then the remaining turkey breast.

Sprinkle with poppy seeds.

Cover the baking dish with aluminum foil and bake for 15 minutes. Remove the aluminum foil and cook for about 5 minutes longer or until the tops of the rolls are toasted and golden brown.

Lift cooked sliders from the baking dish by the parchment/aluminum lining. Slice apart.