Gluten-free apple cake

Ingredients

• 1 1/4 cups rolled oats (gluten-free)
• 1 cup buckwheat flour
• 6 tbsp virgin coconut oil
• 1/2 cup maple syrup
• 2 tsp cinnamon (divided)
• 1 tsp baking powder
• 2 lbs sour and firm apples
• 1/4 tsp nutmeg
• 2 tbsp lemon juice
• 2 tbsp agave syrup
• 1 1/2 tsp arrowroot flour
• 4 tsp coconut sugar (optional)
• 1 tsp speculaas spice (optional)
• cold water (optional)
• coconut oil for greasing
• flour for work surface
• salt