Prep your rhubarb and tightly arrange it in a greased 8-inch cake pan—no big gaps so the top bakes into a clean, cohesive layer.
Make the cherry syrup by simmering cherry juice, lemon zest, lemon juice, and sugar until thickened, then pour it over the rhubarb.
For the batter, whisk eggs and sugar until pale, slowly stream in olive oil, then whisk in yogurt and extracts.
Whisk in dry ingredients just until no flour streaks remain.
Pour over the rhubarb and bake at 350°F for 35–45 minutes until the center springs back and a tester comes out clean with a few moist crumbs.
Let cool 15–20 minutes, run a knife around the edge, and flip onto a plate while still slightly warm so it releases cleanly.
