Now, it’s assembly time. I don’t grease my baking dish. I spread half of the thinly sliced potatoes in an even layer on the bottom. Over this, I spread the entire cooked and drained ground beef mixture in an even layer. Then, I sprinkle one-third of the shredded Colby Jack cheese (that’s 1 cup) over the beef. Next, I layer on the remaining potato slices. Finally, I pour the entire bowl of creamy sauce over the top, making sure to distribute it evenly and letting it seep down through the layers. I use a spatula to gently press everything down so the sauce coats everything.
The final touch is the cheese. I sprinkle the remaining 2 cups of shredded Colby Jack evenly over the top of the casserole. I cover the dish tightly with aluminum foil—this is key to steaming the potatoes and preventing the cheese from burning before the potatoes are tender. I bake it covered for 50 minutes. Then, I remove the foil and bake for another 20-25 minutes, until the top is golden and bubbly, and the potatoes are easily pierced with a fork. I let it rest for 10-15 minutes before serving; this allows the sauce to thicken slightly so it slices beautifully.
Pro Tips for Best Results
For the most flavorful beef, don’t just gray it—let it get a nice brown crust in the skillet. Those browned bits add incredible depth. Also, season the beef well with salt and pepper while it cooks. I’ve tried seasoning only the sauce, and the beef layer itself can taste bland. Seasoning in layers is the secret to a fully flavored dish.
To ensure your potatoes cook through evenly, slice them uniformly. A mandoline is the best tool for this. If they are different thicknesses, you’ll have some crunchy and some mushy potatoes. Also, don’t rinse the sliced potatoes; the surface starch helps thicken the sauce as it bakes.
Letting the casserole rest after baking is non-negotiable. I learned this the hard way when I served it immediately and it was a delicious but soupy mess on the plate. The 10-15 minute rest allows the starches in the potatoes and the sauce to set, making it easy to cut into clean, perfect squares that hold their shape.
Common Mistakes to Avoid
The most common mistake is using the wrong type of potato. Russet potatoes are too starchy and will absorb all the liquid, becoming mushy and potentially leaving the casserole dry. Yukon Golds or even red potatoes have a waxier texture that holds up better and creates a creamier result. Trust me on this swap; it makes a huge difference.
Don’t skip the step of covering the casserole with foil for the first part of baking. If you bake it uncovered the whole time, the top cheese will burn long before the potatoes in the center are tender. The foil creates a steamy environment that cooks the potatoes perfectly.
Avoid overloading the casserole with too many layers. You want just two distinct layers of potatoes with the beef and cheese in between. If you make the layers too thick, the potatoes won’t cook through properly. Keep the potato slices thin and the layers even.(See the next page below to continue…)