You will need:
1 14 oz Hungry Monkey Cinnamon Apple Streusel Cake or store bought apple cake (or you can make your own!)
2 sticks butter, one salted and one unsalted at room temperature (you can leave it out overnight)
2 TBS Maple Syrup (Grade A Amber is great, we like Spring Tree brand and you can purchase it at almost any grocer, Target, Amazon)
2 cups confectioners' sugar
1/4 cup heavy whipping cream
1 tsp real vanilla extract or vanilla bean paste
1/4 tsp cinnamon & 1/8 tsp nutmeg (optional, but yummy)
In a mixmaster or with a hand mixer, beat butter and slowly add the confectioners' sugar and cinnamon, if using. Increase speed to medium high and continue to beat until incorporated and fluffy. Add in maple syrup, vanilla and whipping cream. Continue on high for 5 minutes until extremely light and fluffy.
Cut apple cake lengthwise through the middle, cutting it so you can frost the inside between layers. Spoon on a generous amount of buttercream and smooth it out with an offset spatula or knife. Place the top layer back on. Freeze for 20 minutes. Place another very generous amount of buttercream on top and frost sides with buttercream, using the offset spatula to smooth sides. If they are uneven, simply place your offset spatula under extremely hot water and then use it to smooth the frosting.
Serve within 4 hours or refrigerate. Once refrigerated, you'll need to let the cake sit for an hour before serving so the buttercream softens to the right consistency.