Preheat oven to 325 degree F. Line a cookie sheet with parchment paper, or line cookie sheet with foil and lightly coat with nonstick cooking spray; set aside.
In a large mixing bowl combine oats, sugar, flour, cardamom, salt, and baking powder. In a medium bowl whisk together the egg, butter, and vanilla until well combined. Add egg mixture to the flour mixture; stir until well combined. Add the almonds and stir until evenly distributed.
Drop level teaspoons of dough 3 inches apart on prepared cookie sheet. Bake for 10 to 12 minutes or until edges are brown. Let cookies cool completely, then peel from parchment paper or foil. Repeat with remaining dough.
For each sandwich cookie, spread bottom side of a cookie with a rounded teaspoon of Vanilla Cream. Place a cookie, top side up, on top of filling. Makes 30 to 36 filled cookies.
In a large mixing bowl beat together butter with 1 cup of the powdered sugar until smooth. Beat in vanilla. Gradually beat in the rest of the powdered sugar until mixture is smooth.