Pre-heat your oven to 180C Fan/400F/Gas Mark 6 and line a large baking tray with baking paper
Ideally using a stand mixer with the paddle attachment, mix the butter, caster sugar and light brown soft sugar together until fluffy and paler in colour. This will take 3-5 minutes in an electric mixer (I use speed 3)
Add the egg and vanilla extract and mix in
Add the plain flour, baking powder, bicarbonate of soda and salt and mix them in until just combined. You can put these ingredients in a separate bowl, and mix them together before adding them, if you like
Then mix in the chocolate chips briefly, just to evenly distribute them
Divide the dough into portions, I weighed the dough out to make each cookie croissant an equal size
Using a sharp knife, carefully slice the croissants in half, leaving a bit attached at the back
Separate each portion of cookie dough into one large chunk, and two smaller chunks. Flatten out the larger chunk and place it inside the sliced croissant. Flatten out the two smaller pieces and press them on top of the croissants, one on each side. Do this with all the croissants and cookie dough
Place the cookie croissants onto the lined baking tray and bake for 15-20 minutes, depending on how gooey you want the cookie to be in the middle
Let them cool for 5-10 minutes, so you don't burn your mouth, then enjoy warm, ideally with ice cream! Leftovers can be stored in an airtight container, check your croissant packaging for a best before date
Notes
I recommend using larger croissants for this recipe, for example I used Tesco's Finest croissants.
I used homemade cookie dough for this recipe, but you could use shop bought too if you want to make this an even easier dessert!
Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
I prefer to use unsalted butter for this recipe, but you can also use a baking spread.
I used milk chocolate chips in the cookie dough, you could use dark or white chocolate, or a combination.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.