Step 1: Place sliced peaches and lemon juice in a medium bowl. Sprinkle the arrowroot starch, cinnamon, and salt over them.
Step 2: Stir peaches to coat then add maple syrup and vanilla extract to the peach filling and stir again.
Step 3: Process oats in a food processor Transfer the oat flour to a mixing bowl and whisk in coconut sugar, cinnamon, and salt.
Step 4: Pour melted butter and almond extract into the flour mixture and stir to combine. Fold in the remaining half cup of oats.
Step 5: Transfer the peach mixture to the prepared baking dish. Top with pieces of crumble.
Step 6: Bake in preheated oven for 30 to 40 minutes.