This cake adds a little honey to the sugars to enhance the tart rhubarb. You can make it in a Springform pan (as indicated here) for a round shape or a cake pan will also work but it's trickier getting pretty slices out of the pan though it will still taste great
4 Tbsp. melted unsalted butter, cooled, plus more room temperature for greasing the pan
1 tsp. baking powder
½ tsp. salt
1 cup all-purpose flour, plus more for preparing the pan
2 large eggs
1 large egg yolk
1 1/4 cups sugar, plus 1 Tbsp more for sprinkling
1/4 cup honey
2 Tbsp. orange juice
1/4 cup plain greek yogurt
2 tsp. finely grated lemon zest
1 Tbsp orange zest
6-7 stalks of rhubarb - halved lengthwise if thick
Preheat the oven to 350°. Butter and flour pan.
Whisk baking powder, salt, and 1 cup of all-purpose flour in a medium bowl.
Whisk eggs, egg yolk, 1 1/4 cups sugar, honey, and orange juice, and greek yogurt in a large bowl until thick, about 1 minute. Whisk melted butter, orange, and lemon zest into egg mixture just to combine. Add dry ingredients and fold in until batter is smooth; scrape into prepared pan.
Arrange rhubarb over the batter in whatever pattern you like and let it float on top of the cake
Sprinkle with 1 Tbsp sugar and bake until the cake is golden on top and browned around the sides, 45–55 minutes. Let the cake cool in the pan for 15 minutes. Slide a knife around the sides of the cake to loosen and unmold from the Springform pan. Let cool two hours before serving