Options: Line a 9x13 pan with baking parchment. Or spray with Pam and flour the bottom. Or grease and flour the bottom of a 9x13x2 baking pan.
Preheat oven to 350 deg F. Place rack in middle of oven.
Melt the chocolate and the butter in a 2-quart micro safe container on medium-high heat for a couple of minutes. Stir to complete melting. (Iuse a flat whisk all the way.) Dump in the extracts and stir in the sugar. Beat the eggs in, one at a time. Stir in the nuts. Whisk together the flour, baking powder, and salt and fold into the chocolate mixture.Turn into prepared pan, spreading batter into corners. Bake in center of oven for 30-35 minutes.