1. Preheat oven to 350°F and grease a 9×9 inch baking pan well. Line with parchment paper for easy removal—rhubarb can be sticky.
2. Wash rhubarb thoroughly and trim off any leaves. Cut into chunky ¾-inch pieces—don’t go smaller or they’ll disappear into the cake.
3. Toss rhubarb pieces with 1 tablespoon flour and 2 tablespoons sugar in a bowl. Set aside.
4. In a large bowl, cream butter and 1 cup sugar until light and fluffy, about 3-4 minutes. Add egg and vanilla, mixing until combined.
5. In a separate bowl, whisk together flour, baking powder, and salt.
6. Alternate adding dry ingredients and milk to the butter mixture, beginning and ending with flour. Mix just until combined—don’t overmix.
7. Gently fold in the floured rhubarb pieces, distributing them evenly throughout the batter.
8. Pour batter into prepared pan and spread evenly. Sprinkle top with coarse sugar if using.
9. Bake for 40-45 minutes until top is golden brown and a toothpick inserted in center comes out with just a few moist crumbs.
10. Cool completely in pan before cutting—this helps it set up properly. Dust with powdered sugar before serving if desired.

Notes:

• Don’t skip tossing rhubarb with flour—it prevents sinking and helps distribute evenly
• Room temperature ingredients mix better and create lighter cake texture
• Cut rhubarb into substantial chunks for the best texture and flavor bursts
• Every oven runs differently, so start checking at 40 minutes

Storage Tips:

• Keeps covered at room temperature for 2-3 days
• Actually improves after a day as flavors meld
• Freezes well wrapped tightly for up to 3 months
• Serve with vanilla ice cream or whipped cream for extra indulgence