Preheat your oven to 375°F (190°C).

Carefully slice each croissant horizontally, almost all the way through, creating a pocket.

Open each croissant and spread a generous layer of pesto on both halves.

Tuck slices of fresh mozzarella into the croissant.

If using sun-dried tomatoes, sprinkle them over the mozzarella.

Close the croissants and place them on a baking sheet.

Bake for 10-12 minutes, or until golden brown and the cheese is melted and bubbly.

Garnish with fresh basil leaves, if desired.

Serve warm immediately.