1. Preheat oven to 350 degrees.
2. In a mixing bowl whip butter and brown sugar until light and fluffy. Add egg and vanilla. Beat until well combined.
3. Sift together the flour, cocoa powder, baking soda, and salt in a separate bowl.
4. Add the dry ingredients alternately with the buttermilk to the butter/sugar mixture just until combined.
5. Scoop dough (about 2 Tablespoons each) onto cookies sheets. Be sure to space at least 2 inches apart to allow for spreading. (I used a medium cookie scoop and thought it was a perfect size.)
6. Bake 8-10 minutes or until it springs back when touched.
7. Place half of the cookies upside down. Top with a generous sized amount of strawberry whipped filling. Top with sliced strawberries. Place the second cookie on top. Smear top cookie with approximately 2 teaspoons chocolate glaze.

For Strawberry Filling:

1. Place softened butter in mixing bowl. Whip for 2-3 minutes. Add 1 Tablespoon strawberry jam, confectioners sugar, flour, and vanilla. Beat on medium-high speed for about 3 minutes. Stir in the rest of the strawberry jam.

For Chocolate Glaze:

1. In a microwave-safe bowl melt chocolate chips on 50% power for 1 minute. Stir  well. Continue to microwave in 15-second intervals, stirring after each time until fully melted. Stir in melted butter and agave or corn syrup. Spoon glaze over the top of each whoopie pie.