Directions

• Heat the oven to 350° F. Butter an 8-inch square baking pan and line the bottom with parchment paper.
• Spread the walnuts and coconut flakes evenly in a small baking dish and toast for about 5 minutes, until just lightly browned. Let cool.
• While the walnuts and coconut are toasting, coarsely grate the kiwi into a small bowl, making sure to catch the juice. Small remnants can be finely diced. Add the berries and lemon juice to the grated kiwi and stir to combine. Set aside.
• Meanwhile, in a small skillet over medium heat melt the butter and cook until it turns brown and smells nutty, about 4 to 6 minutes. Be sure to stir frequently, scraping up any bits from the bottom so they don't burn. Take the pan off the heat and let cool slightly.
• In a large bowl, whisk the flour, rolled oats, granulated sugar, brown sugar, toasted walnuts, coconut flakes, lemon zest, salt, and baking soda. Add the browned butter and stir with a wooden spoon until thoroughly combined.
• Press 2/3 of the oat mixture in an even layer on the bottom of the prepared baking pan. Spread the berry-kiwi mixture evenly across the crust, then sprinkle with the remaining oat mixture.
• Bake the bars for about 45 minutes, rotating the pan halfway through baking, until the top is golden brown and the berries are bubbling up around the edges. Transfer the pan to a wire rack and let the crumble bars cool completely. Cut into squares and serve. Bars can be kept in an airtight container on the counter for two or three days, if not longer. They'll soften as they age but retain their texture.