Preheat oven to 350° F. Line a 9-inch cake pan with parchment paper.

In a large, heavy bottomed frying pan, heat ½ cup sugar and rosemary in a saucepan over medium heat.Cook until sugar melts and darkens. Don’t stir; just swish the sugar around by shaking the pan.

Remove from heat and discard rosemary. Add ½ cup sugar (this is where you could add an extra ¼ cup sugar if you like things sweet) and the rhubarb. Return to heat just until the mixture is easy to pour. Don’t worry too much about the consistency. Unlike regular caramels, this one doesn’t have to be perfect since it’s going to be baked in the oven.

Pour into parchment lined pan.

To make cake, beat butter and ½ cup granulated sugar in a bowl with a mixer until fluffy. Add egg whites and vanilla and beat until well blended. Add baking powder and salt and mix. Beat flour mixture in just until combined. Add in yogurt (sour cream works too) until smooth.

Spread batter evenly over rhubarb.

Bake cake until golden brown and a toothpick inserted in center comes out clean, 35+ minutes. Let cool in pan. Invert pan onto a platter. Remove the parchment paper (I keep the parchment paper and pan for the leftovers. It’s easy to place them back on top of the cake and store in the refrigerator without having to dirty any more dishes).

Slice and serve with vanilla ice cream. Happy Father’s Day, to my dad and all the other fathers out there as well.