Keep raspberries frozen until the last moment and fold them in gently at the end to prevent bleeding color and juice into the batter, maintaining those beautiful pockets of fruit.

Chop white chocolate into small pieces and let them sit in the warm batter for 2 minutes before folding to partially melt and distribute creaminess evenly throughout each muffin.

Bring sour cream to room temperature before mixing to ensure smooth incorporation and prevent lumps, resulting in a tender, uniform crumb structure.

Fold ingredients together until just combined—overmixing activates gluten and creates tough, dense muffins; a few lumps are perfectly acceptable and preferable.

Fill muffin cups two-thirds full, then add a few raspberries and white chocolate chips in the center before topping with remaining batter for beautifully distributed mix-ins and level rise.