In a large mixing bowl, combine the ½ cup full-fat plain Greek yogurt, 1 tsp 1 tsp garam masala, ½ tsp ½ tsp ground cumin, ½ tsp ½ tsp turmeric, and ½ tsp ½ tsp kosher salt. Add the 1 ½ lb boneless skinless chicken thighs and toss to coat thoroughly. Cover and marinate for at least 20 minutes at room temperature, or refrigerate for up to 24 hours for deeper flavor.

Melt 1½ tbsp 3 tbsp unsalted butter in a large skillet over medium-high heat. Working in batches if needed, add the marinated 1 ½ lb boneless skinless chicken thighs in a single layer. Sear for 3–4 minutes per side until lightly charred and just cooked through. Remove the 1 ½ lb boneless skinless chicken thighs to a plate and set aside — it will finish cooking in the sauce.

Reduce heat to medium and add the remaining 1½ tbsp 3 tbsp unsalted butter to the same skillet. Add the diced medium yellow onion and cook, stirring occasionally, for 5–6 minutes until softened and golden. Add the 4 cloves garlic and 1 tbsp fresh ginger grated and cook for 1 minute until fragrant. Stir in the 1 tsp garam masala, ½ tsp ground cumin, 1 tsp smoked paprika, and ¼ tsp cayenne pepper adjust; toast the spices for 30 seconds. Pour in the 1 can crushed tomatoes, scraping up any browned bits from the bottom of the pan. Season with 1 tsp ½ tsp kosher salt and simmer for 8–10 minutes, stirring occasionally, until the sauce thickens slightly.

Carefully transfer the sauce to a blender (or use an immersion blender directly in the skillet) and blend until smooth. Return the sauce to the skillet over medium-low heat. Stir in the 1 cup heavy cream and bring to a gentle simmer. Add the seared 1 ½ lb boneless skinless chicken thighs back to the pan and simmer for 8–10 minutes, until the 1 ½ lb boneless skinless chicken thighs is fully cooked through and the sauce is velvety and coats the back of a spoon.

Taste and adjust ½ tsp kosher salt as needed. Ladle the 3 tbsp unsalted butter 1 ½ lb boneless skinless chicken thighs over cauliflower rice or your favorite keto side. Garnish with a drizzle of heavy cream and freshly chopped fresh cilantro roughly chopped. Serve immediately.