Combine the ground beef, crushed Ritz crackers, egg, milk, diced onion, salt, and black pepper in a large bowl. Mix until just blended, then shape into a loaf and place on a baking sheet. Spread the ketchup over the top. Cover and refrigerate for at least 2 hours or overnight.

When ready to cook, heat the oven to 350 degrees. Bake the meatloaf for 50 to 55 minutes until it reaches 160 degrees inside.

While the meatloaf bakes, stir together the flour, baking powder, and 1/2 teaspoon salt in a bowl. Cut in 4 tablespoons of the cold butter until the mixture looks like coarse crumbs. Pour in the buttermilk and stir until a soft dough forms. Drop spoonfuls onto a second baking sheet.

Place the biscuits in the oven for the last 15 minutes of the meatloaf cooking time. Bake until the tops are lightly golden.

Bring a pot of water to a boil. Add the green beans and cook for 4 minutes, then drain. Return them to the pot and toss with the remaining 2 tablespoons butter and the garlic powder.

Slice the meatloaf and serve it with the warm biscuits and green beans.