1. Preheat the oven to 350F.
2. Spray mini Bundt cakelet pans, I made 8 mini cakes or this recipe makes a 10-cup Bundt pan for one large cake.

To make the Cakelets

1. In a medium bowl sift together the flour, baking powder and salt, set aside.
2. In the bowl of a standing mixer, using the paddle attachment, cream the butter, sugar and lemon zest together for about 4 minutes or until light and fluffy.
3. Add the eggs one at a time, scraping down the bowl as needed, stir in the lemon oil.
4. Stir the flour mixture in three additions alternating with the buttermilk, starting and ending with the flour.
5. The batter will be thick.
6. Toss the rhubarb slices with the 2 tablespoons of flour and fold half the rhubarb into the batter.
7. Scrape the batter into the cake pans and sprinkle the remaining rhubarb on top.
8. Bake for 20-22 minutes or until golden brown on edges and the top springs back when pressed.
9. Cool the cakes in the pan for about 10-15 minutes, remove from the molds and continue cooling on a metal rack, placed over a baking pan.

To make the Lemon Buttermilk Glaze

1. Whisk the powdered sugar, lemon juice, buttermilk and butter together in a medium bowl.
2. The mixture should be thick, add additional powdered sugar if needed.
3. Spread the glaze over the cakes as soon as you remove them from the pan.
4. Covered cakes will last up to 4 days at room temperature.