Preheat the oven to 350°F (175°C). Line a 9x9-inch baking dish with parchment paper, leaving an overhang for easy removal. Grind 2-3 dehydrated kiwi wheels in a food processor or spice grinder until they form a fine powder. Set aside 1 teaspoon for the crumble and 1 tablespoon for the filling.

In a medium mixing bowl, combine the flour, oats, brown sugar, salt, and 1 teaspoon of dehydrated kiwi wheel powder. Add the cold cubed butter and use your fingers or a fork to work it into the dry ingredients until the mixture resembles coarse crumbs. Press half of the mixture firmly into the bottom of the prepared baking dish to form an even layer.

In a small mixing bowl, mix the mashed kiwi, granulated sugar, cornstarch, lemon juice, and 1 tablespoon of dehydrated kiwi wheel powder until well combined. Spread the filling evenly over the crumble base.

Sprinkle the remaining crumble mixture evenly over the kiwi filling, pressing lightly to adhere.

Bake for 30-35 minutes, or until the top is golden brown and the filling is bubbly. Remove from the oven and let cool completely on a rack.

Lift the bars out using the parchment overhang and cut into 12 squares. Serve at room temperature, garnished with dehydrated kiwi wheels if desired.