Original recipe used potato slices in the vegetable base and only mayo for a "sauce" in that layer. Original recipe didn't use jalapenos. For a milder version, remove seeds and membranes from the jalapenos. Pepper Jack can replace part of the mozzarella if you prefer a little more heat. I made a few other changes.
Filling
16 oz cream cheese, softened
1 cup shredded sharp cheddar
2 jalapeños, finely diced (remove seeds for less heat)
3 green onions, thinly sliced
½ tsp garlic powder
2 tbsp chopped fresh parsley
Vegetable Base
1 large head cauliflower, cut into bite-size florets
1 large red bell pepper, cut into 1-inch pieces
8 oz mushrooms, sliced
1 large yellow onion, sliced
2 cloves garlic, minced
2 tbsp olive oil
1 tsp kosher salt
½ tsp black pepper
1 tsp Italian seasoning
Sour Cream Sauce
1 cup sour cream
½ cup shredded Parmesan cheese
½ cup shredded mozzarella
1 tsp garlic powder
½ tsp onion powder
¼ tsp smoked paprika
2 tbsp chopped fresh chives
2 tbsp milk or heavy cream (if needed to thin)
Topping
1 cup shredded mozzarella
½ cup shredded sharp cheddar
2 tbsp grated Parmesan
1 jalapeño, sliced into rings
Chopped parsley for garnish
Recipe
1. Prepare the filling. Combine the cream cheese, cheddar, diced jalapeños, green onions, garlic powder, and parsley until smooth. Refrigerate while preparing the beef.
2. Season the beef. Mix the ground beef with the salt, pepper, garlic powder, onion powder, smoked paprika, Worcestershire sauce, and egg until just combined.
3. Form the stuffed beef. Divide the beef into six equal portions. Press each into a bowl or large measuring cup to form a shell, leaving the center hollow. Fill each with the cream cheese mixture, then seal completely, forming large stuffed meatballs or domes. Chill for 30–60 minutes.
4. Cook the vegetables. Heat the olive oil in a large skillet over medium-high heat. Sauté the onion for about 5 minutes. Add the mushrooms and cook until their moisture has evaporated. Stir in the garlic for 30 seconds, then add the cauliflower and red bell pepper. Season with the salt, pepper, and Italian seasoning, and cook another 5–6 minutes until the vegetables begin to soften.
5. Make the sauce. In a bowl, whisk together the sour cream, Parmesan, mozzarella, garlic powder, onion powder, smoked paprika, chives, and enough milk or cream to make a spreadable sauce.
6. Assemble. Heat the oven to 375°F. Spread the vegetable mixture in a 9×13-inch baking dish. Spoon the sour cream sauce evenly over the vegetables. Nestle the chilled stuffed beef domes halfway into the vegetables.
7. Top. Sprinkle with the mozzarella, cheddar, and Parmesan. Scatter the jalapeño rings over the top.
8. Bake. Bake for 50–60 minutes, or until the beef reaches 160°F in the center and the vegetables are tender.
9. Finish. If desired, broil for 2–3 minutes until the cheese is browned and bubbling. Let rest for 10 minutes before serving, then garnish with chopped parsley.