In a large bowl, combine ground turkey and ground chicken, shredded cheese, grated garlic, Italian seasoning, bouillon cube, red chili pepper flakes, half the chopped cilantro or parsley, and black pepper. Mix gently with your hands until just combined, being careful not to overwork the mixture. Form into medium-sized balls about 1.5 inches in diameter (you should get 16-18 meatballs). Arrange the turkey meatballs on a plate and set aside.

Heat olive oil in a 12-inch skillet over medium-low heat. Add the meatballs in a single layer without crowding (work in batches if needed). Cook for 8 to 10 minutes, turning occasionally, until golden brown on all sides and cooked through to 165°F internally. The key is medium heat so the outside doesn't burn while the inside stays raw. Remove to a clean plate and set aside.

In the same skillet with the remaining cooking juices, melt butter over medium heat. Add the minced garlic and cook for about one minute until fragrant but not browned. Stir in the diced onion and cook until translucent, about 3 to 4 minutes. Add the drained sun-dried tomatoes and fry for 1 to 2 minutes. Pour in the vegetable broth and let it reduce for about one minute (liquid should reduce by about one-third).

Lower the heat and pour in the heavy cream, stirring gently. Bring the sauce to a gentle simmer and season with salt and pepper to taste. Add the baby spinach and stir until wilted. Sprinkle in the Parmesan cheese and let the sauce simmer for another minute until the cheese melts and the sauce thickens slightly and coats the back of a spoon.

Return the cooked meatballs to the pan and spoon the creamy sauce over each one. Garnish with the remaining fresh parsley and serve immediately over cauliflower rice for keto or pasta for traditional serving.