In a saucepan or microwave-safe bowl, melt the butter until just melted but not hot. Pour into a mixing bowl and stir in the brown sugar and granulated sugar until combined.

Add the egg and vanilla extract, then stir until smooth.

Sift in the all-purpose flour, spelt flour, baking soda, baking powder, and pinch of salt. Stir until a cookie dough forms with no dry streaks remaining.

Fold in the roughly chopped dark chocolate until evenly distributed throughout the dough.

Cover and refrigerate the dough for at least 1 hour. This helps deepen the flavour and gives the cookies their chewy texture.

When ready to bake, preheat the oven to 350°F and line a baking sheet with parchment paper.

Scoop the dough onto the baking sheet, leaving space between each cookie. Sprinkle the tops lightly with flaked salt.

Bake for about 9–12 minutes, or until the edges are golden and the centres still look slightly soft.

Let the cookies cool on the baking sheet for a few minutes before transferring to a wire rack. They’re especially good while still slightly warm and melty.