Grain-free and low in sugar
Preheat the oven to 400°. Prick the sweet potatoes all over with a fork and roast for 30-40 minutes or until very soft. Make sure to place a baking sheet under sweet potatoes to catch drippings. Allow to cool until easy to handle. Discard the skins and place in a blender, food processor, or use an immersion blender to puree until smooth. Measure out 3/4 of a cup for use in recipe.
Change oven temperature to 350°.
Line both sides of cake pan with parchment paper.
Core the apples and slice in to 1/2 cm thick slices. Place in a bowl and toss with fresh lemon juice to prevent browning. Set aside.
Combine the sweet potato puree with 1 tbsp honey, coconut oil, and eggs. Blend or whisk until combined.
Whisk together the dry ingredients; almond flour, coconut flour, baking soda, cinnamon, cardamom, and salt.
Mix the dry ingredients into the wet mixture until just combined. Pour into cake pan and smooth top. Arrange the apple slices in three vertical lines on top of the cake. Each line should have about 11 apple slices, and each slice should slightly overlaps the other slice.
Bake for 30-35 minutes or until a toothpick inserted comes out clean. Allow the cake to cool in the pan for 15 minutes. Remove from pan and transfer to a cooling rack to cool completely. Slice into 9 squares.