Cut chicken breasts into 1-inch cubes and set aside on a plate. Finely dice the onion into 1/4-inch pieces, mince the garlic and ginger, and measure them into separate small bowls. In another bowl, whisk together the tomato paste, water, salt, garam masala, curry powder, paprika, red pepper flakes, and stevia powder until you have a smooth, unified paste. This spice base is crucial for building layers of flavor without burning individual spices.

Melt 5 tablespoons of butter in a large pan over medium-high heat until it foams and turns golden. Add the diced onion and cook for about 4 minutes, stirring occasionally, until the onions become translucent and slightly softened. This develops a sweet, caramelized foundation that anchors the curry flavor. I like to let the onions get just a touch of color—it adds depth without bitterness.

Stir in the minced garlic and ginger, then immediately add the spice paste from Step 1. Cook for about 1 minute, stirring constantly, until the mixture becomes fragrant and slightly darkened. This blooming process activates the spices and removes any raw flour taste from the ginger and garlic, creating a rich, complex flavor base that won't taste flat.

Add the cubed chicken to the pan and cook for 2 minutes without stirring too much—this allows the chicken to make contact with the hot pan and develop light color. The chicken won't be fully cooked at this point, which is fine; we're building flavor through gentle browning rather than cooking it through.

Pour in the 8 oz of tomato sauce and stir well to combine with the spice mixture. Simmer over medium-high heat for 3 to 5 minutes, stirring occasionally, until the chicken is mostly cooked through and the sauce has melded with the spices. The sauce should bubble gently and thicken slightly as it reduces.

Reduce the heat to medium and pour in the 1/2 cup of heavy cream that's at room temperature. Stir gently and continuously for about 2 minutes until the sauce is smooth and creamy, and the chicken is fully cooked through. I use room temperature cream to prevent the sauce from curdling—cold cream can shock the hot pan and break the sauce. Taste and adjust seasonings if needed, then remove from heat.

Transfer the butter chicken to a serving dish or individual plates and garnish generously with fresh parsley for brightness and color contrast.