Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or line it with parchment paper.

In a medium bowl, combine the chopped rhubarb with 2 tablespoons of granulated sugar. Set aside to let it macerate for about 10 minutes.

In a large mixing bowl, cream together the softened butter and remaining granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In another bowl, whisk together the all-purpose flour, almond flour, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix until just combined.

Fold in the macerated rhubarb gently into the batter.

Pour the batter into the prepared cake pan and smooth the top.

Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Dust with powdered sugar before serving, if desired.