Preheat your oven to 350 degrees F. Grease a 10-inch cake pan well with non-stick spray and set it aside.

In a large bowl, cream together the butter and sugar until they're light and fluffy.

Add the eggs one by one, mixing each one in thoroughly before adding the next.

Mix in the vanilla extract, sour cream, and milk. Blend everything on low speed until combined.

In another bowl, sift together the flour, baking powder, baking soda, and salt. Gradually add these dry ingredients to the wet mixture, mixing on low speed until just combined.

Gently fold in the diced rhubarb with a spatula.

Pour the batter into your prepared cake pan, spreading it evenly. Tap the pan on the counter to remove any air bubbles and ensure the batter reaches all corners.

Bake the cake for about 45 minutes, or until a toothpick inserted in the center comes out clean.

Let the cake cool in the pan for 15 minutes before transferring it to a wire rack to cool completely.

Once cooled, you can dust the cake with confectioner's sugar and serve it with vanilla ice cream if you like.