In a large bowl, combine fresh lemon juice, corn starch, ground cumin, 1/2 teaspoon of ground turmeric, 3 teaspoons of garam masala, and 1 teaspoon of salt. Toss the cauliflower florets gently in this flavorful mixture until evenly coated, then set them aside to marinate for about 10 minutes.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Once the oil shimmers, add the marinated cauliflower florets and cook, stirring occasionally, until they turn golden brown and are tender, about 7 to 8 minutes. Remove the cauliflower from the skillet and set it aside on a plate.

In the same skillet, add another tablespoon of olive oil and the unsalted butter, allowing it to melt over medium heat. Add the chopped yellow onion and sauté until it becomes translucent and soft, roughly 8 minutes. Then, stir in the minced garlic, freshly grated ginger, and tomato paste; cook for an additional 2 minutes until fragrant.

Incorporate the remaining spices: 1/2 teaspoon of ground turmeric, 3 teaspoons of garam masala, 1 teaspoon of salt, paprika, ground cinnamon, and cayenne pepper into the onion mixture. Stir well to combine before adding the tomato sauce and vegetable broth. Bring the sauce to a boil, then reduce the heat and let simmer for about 5 minutes.

Slowly mix the heavy cream into the simmering sauce, creating a rich, creamy texture. Return the sautéed cauliflower to the skillet, stirring gently to coat the florets in the sauce. Allow everything to simmer uncovered for about 15 minutes, stirring occasionally.

Once your Butter Cauliflower is beautifully thickened, remove it from the heat. Garnish with fresh cilantro before serving hot over fluffy basmati rice. Optionally top with whole-milk Greek yogurt.