01 -
Get your stand mixer ready with the paddle attachment. Whip softened butter, white sugar, and brown sugar on medium until the mix is fluffy and smooth—should take about 3 minutes.
02 -
Crack in the egg and pour in vanilla. Slowly mix on low till combined, then increase speed to medium-high for a minute to blend well together.
03 -
If needed, scrape down the sides of the bowl. Add baking soda, salt, and cornflour first, stirring for 30 seconds. Add the flour gradually—about a cup at a time—until it's all mixed in properly.
04 -
Toss in the chopped chocolate chunks and stir gently with a spatula. You can also let the mixer run on low for a bit until the chocolate's evenly spread out.
05 -
Turn your oven on to 350°F (175°C). Cover a baking sheet with parchment paper.
06 -
Using a serrated knife, carefully cut croissants open along one side so they resemble an open book. Don't cut all the way through! Lay them on your prepared sheet.
07 -
Take roughly 1/2 cup of cookie dough for each croissant. Use some of it to spread a thin layer inside the open croissant, making sure it's even. Gently press it back closed.
08 -
With the rest of the 1/2 cup of dough, shape pieces and flatten them in your hands. This dough goes on the outer tops of the croissants on both ends. Keep at it until all croissants are stuffed and topped.
09 -
Pop the stuffed croissants (crookies!) in the oven for 10-12 minutes. You’re looking for the dough on top to turn lightly golden—don’t let it get too dark.
10 -
Take the baking sheet out and let the crookies cool just a bit before serving them warm.