Here is a nice step-by-step "photo tutorial" for you to follow along with the recipe.
Baked Ham & Cheese Sandwiches
original recipe here
3 tablespoons butter
3 tablespoons all-purpose flour
1 cup milk
Pinch of ground nutmeg
Coarse salt and ground pepper
8 slices white sandwich bread
3/4 pound cooked ham, thinly sliced
2 cups shredded Gruyere, or other melting white cheese
Dijon mustard, for serving (optional)
Preheat oven to 400 degrees. Heat butter in a medium saucepan over medium heat until foamy. Add flour; cook, whisking constantly, until smooth, 1 to 2 minutes (do not let color).
Add milk and nutmeg to saucepan. Whisking constantly, bring to a simmer; continue cooking until thickened, 2 to 3 minutes. Season with salt and pepper. Transfer to a shallow dish; cover with plastic wrap, pressing it directly on the surface of the sauce. Refrigerate at least 10 minutes.
Place 4 slices of bread on a baking sheet. Spread each slice with sauce, dividing evenly; layer with ham, and sprinkle each with 1/4 cup cheese. Top with remaining bread; sprinkle with remaining cup cheese. Bake until cheese is melted and golden, about 15 minutes. Serve hot, with mustard on the side, if desired.
***I make as many sandwiches as I need for my family (up to the four the recipe can make). Then, I put whatever leftover sauce I have into a tupperware in the fridge for "fast sandwiches" later on. I also tear up the ham into bite-size pieces for my toddler's sandwich. It's just easier for the little ones to eat it that way.***