Ingredients:

  • 1 Tbsp Vegetable Oil
  • 5 lbs Lean Ground Beef (85/15 preferred)
  • 1 medium Yellow Onion (finely diced)
  • 8 oz Cremini Mushrooms (sliced)
  • 3 cloves Garlic (minced)
  • Kosher Salt & Freshly Cracked Black Pepper (To taste)
  • 4 Tbsp Unsalted Butter
  • 4 Tbsp All-Purpose Flour
  • 1 cup Beef Stock (low sodium, warm)
  • 1 cup Whole Milk (warm)
  • 1 Tbsp Worcestershire Sauce
  • 1/2 tsp Dried Thyme
  • 1 cup Sharp Cheddar Cheese (grated)
  • 1/2 cup Gruyère or Monterey Jack (grated)
  • 32 oz bag Frozen Tater Tots

Instructions:

  1. Preheat the oven to 400°F (200°C). Lightly grease a 9x13 inch casserole dish.
  2. Heat oil in a large skillet over medium-high heat. Add ground beef and season generously with salt and pepper. Cook, breaking up the meat, until no pink remains (about 5-7 minutes). Drain off all excess grease meticulously and return the beef to the skillet.
  3. Reduce heat to medium. Add diced onion and mushrooms to the beef. Cook until the vegetables soften and the mushrooms have released their moisture (about 6-8 minutes). Stir in the minced garlic and thyme, cooking for 1 minute until fragrant. Remove the beef mixture and set it aside.
  4. Make the Roux: Return the empty skillet to medium heat. Melt the 4 Tbsp butter. Whisk in the 4 Tbsp flour until a smooth paste forms (the roux). Cook the roux for 1-2 minutes, stirring constantly, to cook out the raw flour taste.
  5. Build the Sauce: Gradually whisk in the warm beef stock until fully incorporated and lump-free. Then, gradually whisk in the warm milk. Bring the mixture to a gentle simmer, stirring frequently, until the sauce thickens considerably (3-5 minutes). Remove from heat.
  6. Finish Sauce and Combine Filling: Stir in the Worcestershire sauce and adjust seasoning. Add the reserved beef and vegetable mixture back into the sauce. Stir until everything is evenly coated.
  7. Assemble: Pour the creamy beef filling into the prepared casserole dish, spreading it into an even layer. Sprinkle the shredded Cheddar and Gruyère evenly over the filling. Place the frozen tater tots across the top in a single, tight layer.
  8. Bake and Rest: Bake for 30-35 minutes, or until the filling is bubbling hot and the tater tots are deeply golden brown and crisp. Remove from the oven and let the casserole rest for 5 minutes before serving.