Prep the mushrooms. Finely chop all the mushrooms.
Set aside about 1 cup for the meatballs and keep the rest for the sauce. The smaller you chop, the better they blend and hold moisture.
Sauté the aromatics. In a large skillet over medium heat, add 1 tbsp oil and 1 tbsp butter. Cook half the garlic and the diced onion until soft and fragrant, 2–3 minutes.
Add the portioned mushrooms for the meatballs and cook until most moisture evaporates, 3–4 minutes. Cool slightly.
Mix the meatballs. In a bowl, combine ground meat, sautéed mushroom mixture, egg, Parmesan, almond flour, 1 tbsp chopped parsley, 1/2 tsp salt, 1/2 tsp pepper, 1/2 tsp smoked paprika, and a pinch of onion powder. If using, add 1 tsp Dijon.
Form the balls. With damp hands, roll into 1.5-inch balls.
You should get 16–20 meatballs. Chill in the fridge for 10–15 minutes to help them hold shape.
Brown the meatballs. Return the skillet to medium-high heat with a drizzle of oil. Brown meatballs on all sides, 6–8 minutes total.
Transfer to a plate; they’ll finish cooking in the sauce.
Make the mushroom sauce. In the same skillet, add the remaining butter. Stir in the rest of the mushrooms and a pinch of salt. Cook until browned and the pan fond loosens, 5–7 minutes.
Add the remaining garlic and cook 30 seconds.
Deglaze and simmer. Pour in the broth, scraping up brown bits. Simmer 2 minutes to reduce slightly. Stir in heavy cream and a pinch of red pepper flakes if you like heat.
Simmer on medium-low until slightly thickened, 3–5 minutes.
Finish the dish. Return meatballs and any juices to the pan. Simmer gently 5–7 minutes, until cooked through (internal temp about 165°F for poultry, 160°F for beef/pork). If the sauce gets too thick, add a splash of broth or cream.
Brighten and serve. Add a little lemon zest and a squeeze of juice to wake up the flavors.
Sprinkle with chopped parsley or thyme. Taste and adjust salt and pepper.
Serve ideas. Enjoy over cauliflower mash, sautéed spinach, or zucchini noodles. Spoon extra sauce over the top and finish with a dusting of Parmesan.