Ingredients :

• Cream cheese — You need it for two parts: the batter and the filling. Two 225g blocks. The Philadelphia brand remains the benchmark for baking stability — generic versions are often runnier and the filling collapses. Take it out of the fridge at least 30 minutes before, otherwise you’ll be fighting lumps.
• Blueberries — Fresh is ideal in season. Frozen works too — but don’t thaw them; fold them in directly frozen to prevent them from turning the whole batter purple. Raspberries or blackberries work if you have neither.
• Heavy cream or whole yogurt — Both work, but the result isn’t identical. Heavy cream gives a richer, denser crumb. Whole yogurt lightens the texture slightly and adds a pleasant tang. Absolutely avoid low-fat versions — you lose all the moistness.
• Butter — Softened, not melted — the nuance really matters. Softened butter creams with the sugar, creating air bubbles and helping the cake rise properly. Melted butter gives a more compact texture. Take it out at the same time as the cream cheese.