Ingredients
Equipment
Method
Prep and bake
- Preheat oven to 350°F and grease a 9x13-inch baking pan. Make sure the pan is evenly coated so the cake releases cleanly.
- Whisk together all-purpose flour, sugar, baking soda, and salt in a mixing bowl. Whisk until the dry ingredients are uniform in color with no visible clumps.
- Mix buttermilk, vegetable oil, eggs, and vanilla extract in a separate bowl. Stir just until the mixture looks smooth and glossy.
- Pour the wet ingredients into the dry ingredients and stir until just combined. Stop when no dry streaks remain and the batter looks thick, not overmixed.
- Fold in fresh rhubarb, diced until evenly distributed throughout the batter. You should see pink pieces suspended across the batter rather than pooled in one spot.
- Spread the batter into the prepared pan and level the top. Tap the pan lightly to settle the batter for even baking.
- Mix sugar and cinnamon and sprinkle evenly over the batter. Aim for an even dusting so every bite gets a sweet, spiced top.
- Bake at 350°F for 40-45 minutes until golden and a toothpick comes out clean. The center should spring back lightly and the edges should look set.
Cool and serve
- Cool the cake for 30 minutes before serving. The top will firm slightly and the rhubarb juices will thicken so slices stay intact.
Notes
Pro tip: If your rhubarb is very wet, pat it lightly with a paper towel before folding it in to keep the crumb tender rather than soggy. Store covered in the refrigerator up to 4 days; freeze slices up to 2 months (thaw overnight in the fridge). For a lighter option, use low-fat buttermilk and replace up to half the vegetable oil with unsweetened applesauce for a similar moist texture.