1 teaspoon mustard (optional – more kid-friendly without it!)
½ teaspoon black pepper
Lay the sliced of bread on a baking tray lined with parchment paper. Toast in a 450 degree oven for a few minutes on each side until golden brown.
While the bread is toasting, melt the butter in a small saucepan. Incorporate the flour, stirring continuously for 30 seconds. Gradually introduce half of the milk, stirring vigorously until the sauce achieves a smooth consistency. Follow by adding the remaining milk and mixing thoroughly. The mixture should gradually thicken, forming a smooth, thick paste.
Incorporate the grated cheese, mustard, and black pepper, then continue to cook for an additional minute or two, while stirring continuously. This process will result in the cheese melting completely and the mixture becoming smooth in texture.
Using a spoon, distribute the sauce onto the untoasted side of each bread slice, and gently spread it to the edges using the back of the spoon. It’s fine if it spills over the edges.
Return to oven for 5 minutes until the cheese is melted and golden brown. Serve and enjoy!