Prepare the oven and preheat to 175 degrees C or 350 degrees F.
Brush melted butter in a 9×13-inch baking dish.
Place a saucepan on the stove and turn the heat to medium-high.
Add 2 tablespoons of butter and allow it to melt.
Add in flour and cook while stirring for 1 minute.
Remove from the heat and add in milk. Whisk until well mixed.
Put it back on the heat and simmer. Stir continuously until done.
As soon as the sauce becomes thick, remove it from the heat.
Season with salt and pepper to taste.
Place a skillet on the stove and turn the heat to medium.
Add butter and allow it to melt.
Add in onions and cook until golden brown.
Season with salt and pepper to taste.
Add 1/3 of the white sauce on the bottom of the prepared baking dish and spread it evenly.
Place half of the potatoes over followed by layers if onions, ham, cheese, and 1/3 of the white sauce.
Sprinkle salt and pepper on top. Repeat this method until all the ingredients are arranged in layers.
Place it inside the preheated oven and bake for 45 minutes or until golden brown.
Remove from the oven and allow it to cool at room temperature.
Serve and enjoy!
Note:
Make sure to use freshly grated cheeses for a quick melt.
