Vietnamese Coffee Cake

For the cake

• 210 grams (1 1/2 cup or 7.4 ounces) plain flour
• 105 grams (3/4 cup or 3.7 ounces) whole wheat flour
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 3 tablespoons instant coffee, ground into a fine powder
• 1/2 teaspoon ground cardamom (or a little less, if you're not used to the flavor)
• 1/2 teaspoon salt
• 90 grams (1/2 cup or 4 ounces) granulated sugar
• 210 grams (1 cup or 7.4 ounces) brown sugar
• 113 grams (1/2 cup or 4 ounces) butter, unsalted and room temperature
• 285 grams (1 1/4 cups or 10 ounces) plain yogurt, full fat
• 1/2 teaspoon vanilla extract
• 2 eggs

For the brigadeiro

• 395 grams (one 14-ounce tin) sweetened condensed milk
• 3 tablespoons strongly brewed coffee (I used some homemade cold brew)
• 1 tablespoon butter, unsalted
• 60 grams (1/4 cup or 2 ounces) heavy cream (optional)

1. Preheat your oven to 180° C/350° F. Grease and line the bottom of a 24.5-cm/9.5-inche round cake tin. Set aside.
2. Into the bowl of a standing mixer (or in a large bowl, if mixing by hand), mix butter and both sugars for about 3 to 5 minutes, or until very light and fluffy. Add in the eggs one at a time, mixing very well between each addition. Meanwhile, mix in the ground instant coffee with the yogurt, until it's somewhat dissolved. In another bowl, whisk both flours, baking powder, baking soda, salt, and ground cardamom. Set both aside.
3. Add half of your dry ingredients into the butter, on low speed, and mix. Then add half the yogurt, mix, then the remaining flour and yogurt, and mix until combined. This process assures that your batter won't curdle. Pour it into the prepared tin and bake it for around 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
4. While your cake cools, make your brigadeiro. In a saucepan, combine the condensed milk, the coffee, and 1 tablespoon of butter. On medium-low heat, keep mixing it with a wooden spoon until it thickens and kind of peels off from the bottom, then turn off the heat. You could leave it like that, but I add a bit of heavy cream to make it more loose—but that's up to you, really. Pour the brigadeiro on top of the cake and it's ready to serve.