Preheat oven to 375°F and grease a cupcake tin.
In a bowl, whisk the dry ingredients and set aside.
In a separate bowl,mix the wet ingredients until well combined (about 2 minutes).
Mix in the dry ingredients into the wet ingredient bowl and continue stirring for 2-3 minutes.
With a spoon, pour the batter evenly into the cups.
Bake for 15-18 minutes
Note: You can test to see if it is done by inserting a toothpick into the center. If the toothpick comes out clean, it is done.
In a medium bowl, mix the powdered Swerve and butter.
Slowly stir in the vanilla and heavy cream.
Gradually beat in remaining milk until frosting smooth
Note: If frosting is too thick, beat in more milk, a few drops at a time. If frosting becomes too thin, beat in a small amount of confectioners Swerve.
Separate 1/3 of the frosting in a bowl and add green food coloring to the remaining frosting until you have the desired color.
Add uncolored frosting to tops of the cupcakes.
Spoon green frosting into piping bag with a flower tip and pipe trees on top of uncolored frosting.