1. Preheat the oven to 375°F | 190°C with a rack in the top third of the oven. Generously butter the inside of an 8-inch| 20 cm square baking dish (or equivalent), then sprinkle with lemon zest.
2. In a bowl, mix together the oats, almonds, baking powder, and salt. In another bowl, whisk together the maple syrup, kefir, water, egg, half the butter, and the vanilla.
3. Arrange the pluots in a single layer in the bottom of the prepared baking dish. Cover the fruit with the oat mixture. Slowly drizzle the kefir mixture over the oats. Gently give the baking dish a couple of raps on the countertop to make sure the liquid moves through the oats.
4. Bake for 35 to 45 minutes, until the top is nicely golden and the oat mixture has set. Remove from the oven and let cool for a few minutes. Drizzle the remaining melted butter on the top and serve. Finish with a bit more maple syrup if you want it a bit sweeter, and a thread of cream to bring it all together.