Preheat oven to 350 degrees.
Prepare a cupcake pan with liners and set aside.
Prepare buttermilk mixture by add vinegar to almond milk and allow to sit while you get the rest of the recipe together.
In the bowl of an electric mixer, add the softened margarine and sugar. Cream together until light and fluffy. Add the Mott's® Original Applesauce.
In a separate bowl, whisk together the dry ingredients.
Alternately add the buttermilk mixture with the dry ingredient mixture, scraping down the sides of the bowl as you go.
Fold in the grated squash and walnuts by hand.
Using an ice cream scoop, fill cupcake liners 3/4 full.
Bake for 15-20 minutes or until a toothpick inserted comes clean.
Allow to cool completely.
To make the maple buttercream frosting, place the cream cheese and margarine in the bowl of an electric mixer on medium speed until light and fluffy.
Reduce the speed to low and add the powdered sugar, almond milk and maple syrup. Beat until smooth and creamy.
If it seems to thick to spread, add more almond milk. Too thin? Add more powdered sugar.
Frost the cupcakes and sprinkle with the chopped walnuts.
Serve immediately or cover and refrigerate to store.