Generously grease & flour a 10" springform pan. Preheat oven to 350 degrees.
In a small pan, combine the sliced almonds and 1/3 cup pure maple syrup. Cook over medium-high heat just until the maple syrup begins to boil, then remove from heat and set aside.
In a large bowl, beat together the coconut oil, almond meal, spelt flour, cardamom, cinnamon, nutmeg, and eggs. Stir together just until mixed. Pour into the prepared pan.
Press the plum halves lightly into the batter. Cover the remaining top of the batter with the mapled almonds.
Bake in preheated oven for 45-50 minutes, or just until the cake is set. Remove and cool completely before popping your cake from the springform pan.
In a large bowl, beat together the cream and powdered sugar just until the cream comes to a very soft peak. Serve over slices of the cake with a mug of your favorite hot drink