Preheat the oven to 350 degrees F. Butter an 8-inch square baking dish.
Melt the butter in a small saucepan. Turn off the heat and let cool slightly, then add the brown sugar, almond and vanilla extract and stir until smooth. Stir in the egg.
Whisk together the flour and baking powder in a small bowl, then fold the mixture into the brown sugar mixture. Fold in the pecans. Pour the batter into the prepared baking dish and bake until set around the edges but still loose in the center, about 20 minutes. Let cool completely, then sift confectioners' sugar on top. Cut into 16 squares.