Step 1

Using a stand mixer fitted with the paddle attachment or a hand mixer fitted with the double beaters, cream the butter and both sugars together until pale and fluffy. You can also use a large balloon whisk and do it by hand.

Step 2

Add the egg, egg yolk and vanilla bean paste, and mix until fully combined.

Step 3

Sift together the gluten free flour blend, xanthan gum, baking powder, baking soda and salt. Add the dry ingredients to the wet in two batches, mixing well after each addition. (If mixing by hand, switch to a wooden spoon for this and all the following steps.)

Step 4

Add in the chocolate chips and half of the chopped chocolate, and mix well until evenly distributed.

Step 5

Chill the cookie dough in the fridge for about 1 hour (in a bowl covered tightly with cling film) until firm enough to scoop and handle easily.

Step 6

Use a "2 tablespoon" ice cream or cookie scoop to scoop individual portions of cookie dough. You should get 16 cookies in total.Place them onto a baking sheet lined with baking/greaseproof paper, cover tightly with cling film and chill in the fridge for at least 30 minutes.Tip: The cookies will be even better if you chill them overnight before baking.

Step 7

Adjust the oven rack to the middle position, pre-heat the oven to 350ºF (180ºC) and line another baking sheet with baking/greaseproof paper.Tip: You will bake the cookies in several batches, so you can line 2-3 baking sheets if you have them on hand. Otherwise, just re-use the same baking sheet, but make sure to cool it completely before you place the next batch of unbaked cookies onto it.

Step 8

In batches (at most, 6-8 at a time), place the chilled cookie dough balls on the lined baking sheet, leaving plenty of space between them (about 2 inches/5 cm), as they will spread out during baking.

Step 9

Bake the cookies at 350ºF (180ºC) for 12-15 minutes in total, depending on your preferred cookie texture and consistency (a shorter time will give you very gooey cookies, a longer baking time will give you more fudgy cookies). They should be light golden on top and golden brown around the edges when done.At the 8-9 minute mark, take the baking sheet out of the oven, tap/bang it 5-7 times onto the kitchen counter, and place a few pieces of the reserved chocolate on top of each cookie.Return the cookies to the oven and bake until done. You can tap the baking sheet again at 2-minute intervals until the cookies are baked, to give them an extra rippled, crinkled appearance, if you wish.Tip 1: Tapping the cookie sheet on the kitchen counter helps the cookies to flatten, thus giving them their characteristic shape and appearance. Omit the tapping if you want thicker cookies.Tip 2: Adding the reserved chopped chocolate to the tops of the cookies halfway through baking will give you those gorgeous glossy puddles of melted chocolate.

Step 10

Immediately out of the oven, you can correct the shape of the cookies into a more evenly round one. To do this, use a round cookie cutter slightly larger than the cookie diameter to nudge the cookies into shape.

Step 11

Allow the cookies to cool on the baking sheet for about 5 minutes, then transfer to a cooling rack to cool completely.

Step 12

Repeat the baking instructions for the remaining balls of cookie dough, then once all the cookies are baked and cooled, sprinkle with flaky sea salt (optional) before serving.

Step 13

Storage:The gluten free chocolate chip cookies keep well in a closed container at room temperature for about 1 week. Note that the cookies will get a bit softer and chewier with time.Alternatively, you can store raw, unbaked balls of cookie dough in an airtight container in the fridge for about 1 week, or in the freezer for 1-2 months. Bake the cookie balls directly from chilled or frozen, just adding 2-3 minutes to the baking time to compensate. Note that the longer the cookie dough balls are in the fridge or freezer, the less they will spread during baking (so the thicker the results).