1/2 cup (1 stick) unsalted Butter, room temperature, plus more for the pan
1 1/2 cup All-Purpose Flour
1/2 cup Almond Flour
2 teaspoons Baking Powder
1 teaspoon Salt
3/4 cup Granulated Sugar
1 teaspoon Vanilla Extract
2 large Eggs
1 cup plain Greek yogurt
Place a rack in the middle of the oven and preheat to 325°. Lightly coat an 8-inch square baking pan with softened butter. Cut two rectangles of parchment paper long enough to line the bottom and two sides of the pan with about two inches extra overhanging the sides. Fit one piece of parchment into the pan; butter the bottom. Fit the second piece on top crosswise, so that all four sides of pan are lined.
Place the rhubarb in a large strainer set over a bowl and let drain; reserve can liquid.
In a medium bowl, whisk together all-purpose flour, almond flour, baking powder, and salt. In a large bowl, beat butter and sugar with an electric mixer until light and fluffy, about 2 minutes. Add eggs one at a time and beat until mixture is pale in color, another two minutes. Beat in vanilla extract. With mixer on low speed, add flour mixture in two batches, alternating with yogurt. Scrape batter into the pan and smooth the top. Top with drained rhubarb.
Bake until cake is golden-brown and a toothpick or cake tester inserted in the middle comes out clean, 60 to 70 minutes. If cake begins to brown too much, tent with foil. Transfer to a wire rack and let cool in pan. When ready to serve, use the parchment overhang on two sides as handles to lift cake out of the pan.