If you have leftover mashed potatoes as I had after making hot pockets with potatoes, put it to work. In my experience re-heating mashed potatoes never worked. I tried oven, cast iron, steam, but it wouldn't come out tasty.
Until I tried this dish. I don't even know its name—moussaka? lasagna?—but it is worth having one! My friend shared this recipe, or rather description, via email. It stuck in my head because of a creative allegory she used: she called a middle layer "an oreo stuffing"
Meat And Potatoes Layers
1 lb meat—I used ground beef
1 cup chopped onions
1/2 cup pine nuts, toasted
Salt+ground black pepper
leftover mashed potatoes—about pound and a half
1 whole egg
1/4 cup heavy cream
1/4 cup plain (or seasoned) bread crumbs (optional)
In a frying skillet, brown beef and add onions, pine nuts, salt+pepper
Preheat oven to 350°F; layer a lasagna pan with 1/2 mashed potatoes;
Layer browned beef;
Top with bread crumbs. Bake in the preheated oven for 40 minutes. Remove from the oven and let cool for 10 minutes before serving. Serve with a dollop of sour cream on a side.
If you don't like beef, you can layer fried beans or greens, such as spinach or kale, sautéed with onions—as long as there's an 'oreo stuffing' inside!