Preheat your oven to 200°C (400°F). If using an air fryer, preheat it to 180°C (350°F). Wash your fresh strawberries, pat them dry, and cut them into small, bite-sized pieces.

Add the egg, egg yolk, and 6 g sugar to a bowl. Pour in 100 ml heavy cream and 30 ml strawberry milk. Whisk gently until the mixture is fully combined.

Be careful not to whisk too vigorously to prevent creating too many air bubbles.

For the absolute silkiest texture, strain the entire custard mixture through a fine-mesh sieve into a jug or another bowl. This crucial step removes any undissolved egg strands and bubbles, guaranteeing a perfectly smooth filling after baking.

Arrange your ready-made tart shells on a small baking tray. Slowly pour the strained custard into the shells, filling each one only about 80% full. This leaves necessary room for the custard to puff up slightly in the oven without overflowing.

Place the baking tray in the preheated oven and bake for 12-15 minutes, or until the custard is set around the edges but may still have a slight jiggle in the very center. The tops should be lightly golden. If using an air fryer, bake at 180°C for about 10 minutes.

Remove the tarts from the oven and let them cool on a wire rack for a few minutes. They will deflate slightly as they cool, which is normal.

Spread a layer of strawberry jam into each tart. Add strawberry pieces on top and garnish with rosemary if desired.