Line 2 baking sheets with parchment paper. Preheat the oven to 190 ° C top / bottom heat.
In a large bowl, beat the butter and sugar until frothy. Add the egg and whisk together well. Sift the flour into the foamy mixture and work everything into a soft dough. Stir in chocolate and Brazil nuts. Using a teaspoon, spread 24 small dough piles on the prepared baking sheets. Leave enough space between the piles as they will come apart when baking.
Place the dough in the preheated oven and bake for 10-12 minutes until golden brown. Place the finished biscuits on a wire rack and let them cool down.
Variations:
The white chocolate can optionally be replaced with whole milk or dark chocolate.