In a large mixing bowl, beat eggs, sugar, pumpkin, and melted butter until smooth. Add remaining ingredients and beat for 2-3 minutes until fully combined.

Pour batter into a lightly greased 15x10x1 inch baking sheet. Bake at 350°F for 25-30 minutes.

Remove from oven and cool completely before frosting.

For the frosting, combine brown sugar, 2 Tbsp butter, and milk in a small saucepan over low heat. Whisk until sugar dissolves. Remove from heat and cool completely.

In a large mixing bowl, beat 1/2 cup softened butter with powdered sugar. Pour in cooled brown sugar mixture. Beat for 3-4 minutes until light and fluffy. Fold in chopped pecans.

Spread frosting over cooled pumpkin bars. Gently press pecan halves into the top of the bars. Cut and store in an airtight container in the refrigerator or freeze until ready to serve.