Preheat oven to 375 degrees F.
Grease and flour a 13 by 9 by 2-inch pan. In a bowl, beat the eggs and butter together; add the brown sugar, then gradually add the flour and mix well. Stir in the vanilla. Spread the batter in the prepared pan and bake for 25 to 30 minutes. Cool and cut into squares.
Prepare the pudding according to the package directions. Let cool slightly. Crumble the blondies into chunks, put them back into the glass dish, and sprinkle with sherry. Spoon the pudding over the blondies. Beat the cream with the sugar just until stiff peaks form. Spoon the whipped cream onto the completely cooled trifle. Refrigerate until serving time.
Add mint to garnish.