Preheat the oven to 350ºF. Lightly grease a 12” cast iron skillet with Brummel & Brown Organic Buttery Spread with Yogurt, and dust it with flour, shaking off any excess. Set aside.
In a medium bowl, whisk together the flour, baking powder, salt, and cinnamon. In a large bowl, whisk the melted Brummel & Brown Organic Buttery Spread with Yogurt, maple syrup, almond milk, lemon juice, vanilla, and apple cider vinegar.
Sprinkle the dry ingredients over the wet, and fold them in using a silicone spatula. Fold in 1 cup of sliced plums. Pour into prepared skillet and top with remaining 1/4 cup sliced plums.
In a high speed blender or food processor, grind the walnuts into a fine meal. Empty them into a medium bowl, and whisk with flour, and salt (only if nuts are not salted). Add Brummel & Brown Organic Buttery Spread with Yogurt and maple syrup, and mix with a spatula until you’ve got a wet sand-like texture. Sprinkle evenly over the top.
Bake 30-35 minutes, until golden brown at the edges and a toothpick or knife inserted in the middle comes out clean. Cool at least 10 minutes before serving.