Place the potatoes into a large pot and cover with salted water. Bring to a boil over high heat, then reduce heat to medium-low, cover, and simmer until tender, about 20 minutes. Drain and allow to steam dry for a minute or two. Return potatoes to the pot. Mash potatoes and butter using a potato masher. Season with salt and pepper.
Heat a large skillet over medium-high heat and stir in the ground beef. Stir in the onions when the beef begins to brown. Cook and stir until the beef is crumbly, evenly browned, and no longer pink. Drain and discard any excess grease. Stir in the beets and mashed potato, and spread the mixture into a 9x13-inch baking dish.
Bake in the preheated oven until lightly browned on top, about 20 minutes.
176.82 calories; 8.62 g protein; 18.92 g carbohydrates; 2.74 g dietary-fiber; 3.01 g sugars; 7.57 g fat; 3.65 g saturated-fat; 31.28 mg cholesterol; 99.18 IU vitamin-a-iu; 4.26 mg niacin-equivalents; 0.36 mg vitamin-b6; 19.62 mg vitamin-c; 29.02 mcg folate; 21.74 mg calcium; 2 mg iron; 32.58 mg magnesium; 516.89 mg potassium; 116.67 mg sodium; 0.1 mg thiamin; 68.17 calories-from-fat; 42 percent-of-calories-from-carbs; 38 percent-of-calories-from-fat; 19 percent-of-calories-from-protein; 18 percent-of-calories-from-sat-fat
I used to make this for the kids when they were little quite often. Only I added a can of sweet corn along with a few sliced mushrooms into the ground beef and onions as they browned. I served the beets warm as a side dish instead.
This dish was really good. My aunt didn't like it so much but my 3 year old brother ate it and loved all of it. I used fresh garden beets and accidentally didn't cook them all the way but other than that I enjoyed it and I don't really care for beets!