Preheat the oven to 350˚F. Line a baking sheet with parchment paper.
Slice the croissants in half and arrange them onto the prepared baking sheet. Set the top halves aside.
In a large bowl, add in the butter, granulated sugar, and brown sugar. Cream the butter and sugars together until creamy and fluffy. Mix in the egg, vanilla extract and almond extract until well combined. Then mix in the lemon zest, grated carrot, almond flour, salt, cinnamon, ginger, and nutmeg. Mix until everything is incorporated.
Brush the insides of the tops and bottoms of the croissants with the simple syrup. Transfer the carrot cake filling into a piping bag. Pipe some of the filling onto the bottom croissants. Then top with the top halves. Spread a thin layer of the remaining filling onto the tops of the croissants. Sprinkle half of the chopped pecans on top.
Bake the croissants in the oven for about 18-20 minutes until the paste has dried and the croissants are crispy on the outside. When they're done, remove them from the oven and set them aside to cool for about 10 minutes until slightly warm.