Preheat your oven to 375°F (190°C) and grease a 10-cup bundt pan with coconut oil.

Blend gluten-free old-fashioned oats until they reach a fine oat flour consistency.

In a large mixing bowl, whisk together the oat flour, blanched almond flour, arrowroot powder, ground cinnamon, apple pie spice, and baking powder.

In another bowl, combine the almond milk, melted coconut oil, pure maple syrup, and unsweetened apple sauce and blend until smooth.

Gently fold the wet mixture into the dry mixture until just combined, then fold in the diced fresh apples.

Pour the batter into the prepared bundt pan, smoothing the top with a spatula.

Bake for 45-50 minutes until golden brown and a knife inserted into the center comes out clean.

Cool the cake in the bundt pan for 20-30 minutes, then invert it onto a wire cooling rack.

Prepare the glaze by whisking powdered sugar with plant-based milk until smooth and drizzle over the cooled cake.