Gently melt 200 g butter in a small saucepan or the microwave, and let it cool slightly.
Whisk 3 pcs eggs, 250 g sugar and 2 tsp vanilla sugar together in a large mixing bowl until light and fluffy.
Add the melted butter and stir gently into a smooth batter.
Mix 200 g plain flour, 1 tsp baking powder and 1 knivspids salt in a separate bowl, and gently fold it into the egg mixture.
Divide the batter into two equal portions in separate bowls.
Add 40 g cocoa powder to one half, and stir thoroughly into an evenly dark batter.
Line a baking tin that fits in your air fryer with baking paper.
Add alternating spoonfuls of the light and dark batter to the tin until all the batter is used up.
Gently draw a knife or a wooden skewer through the batter in a few lines lengthwise and crosswise to create the characteristic tiger-stripe pattern. Be careful not to mix the batters together completely.
Cooking in the air fryer
Place the tin in the preheated air fryer and bake at 160 °C for 22-25 minutes.
Test with a toothpick — it should come out with a few moist crumbs (not wet batter) for a moist brownie. Bake a few extra minutes if the batter is still too wet.
Take out the tin and let the brownie rest in the tin for at least 15 minutes so it sets, before you cut it into squares.
Notes
Tips for the perfect result:
Feel free to brown the butter lightly before mixing it in — it gives the brownie a deeper, nutty flavour. Make sure the two batters have the same consistency, so the striped pattern stays distinct and doesn't blur together during baking.Variation:
Add a handful of coarsely chopped walnuts or dark chocolate chunks to the dark batter for extra texture and depth of flavour. You can also swap the vanilla sugar for ground vanilla for a more intense vanilla flavour.Serving:
Serve the brownie warm with a scoop of vanilla ice cream, whipped cream or a good cup of coffee. It also tastes excellent cold the next day.Portion size:
The recipe makes 4 large portions. Cut the brownie into 8-12 smaller pieces if you're serving it as a dessert-table treat or for lots of guests. If your air fryer is smaller, you can divide the batter and bake in two batches.