Topping: combine all the ingredients in a bowl and rub with your fingertips until you have a crumbly mixture. Place in the fridge.
In a food processor, cream together the butter and brown sugar. Stir in the agave syrup, honey, vanilla extract and the eggs. When the batter is smooth, add the pumpkin puree and stir again.
In another bowl, combine flour, baking powder, baking soda and spices. Carefully add to the pumpkin mixture in the food processor, blending constantly.
Peel the apples and cut into slices
Pour half of the batter in a greased cake pan and cover with apple slices. Pour the rest of the batter on top. Cover with grain/crumble mixture. Bake for 70-80 minutes. Your knife should come out clean when the cake is ready