1. 1. Preheat the oven to 350°F (180°C) and grease a round cake pan.

2. 2. In a bowl, mix together 1 can of condensed milk, 2 eggs, 1/2 cup of melted butter, and 1 cup of brown sugar until well combined.

3. 3. Add 1 cup of blueberries and gently fold them into the batter.

4. 4. In a separate bowl, sift together 1 1/2 cups of all-purpose flour, 1/4 cup of cocoa powder, 1 teaspoon of baking powder, and 1/2 teaspoon of baking soda.

5. 5. Gradually add the dry ingredients to the wet ingredients while alternating with 1 cup of whole milk. Mix until smooth.

6. 6. Pour the batter into the greased cake pan and bake for 40-45 minutes or until a toothpick inserted into the center comes out clean.

7. 7. Let the cake cool before serving.