Place butter in large microwave-safe glass bowl. Microwave, uncovered, on high power for 1 minute. Add the sugar; beat on medium-high speed until the mixture is smooth, about 1 minute. Add the vanilla, almond extracts and the eggs; beat on medium-high speed for about 1 minute or until the mixture is well blended.
Whisk together the flour, baking powder, baking soda and salt in a small bowl until well combined. On low speed, beat the flour mixture into the butter mixture until well blended, for 1 to 2 minutes.
Fold in almonds and chocolate pieces. Pour into a greased 8-inch-square microwave-safe glass baking dish. Cover with plastic wrap. Microwave on high power for 3 minutes, turning the dish around 180° halfway through the cooking. Uncover. Microwave on high power for 4 minutes, turning the dish around 180° halfway through cooking; chewies are done when small knife inserted into center comes out with only a few moist crumbs on it.
Transfer dish to wire rack and let cool completely. With small sharp knife, cut into 16 squares.
In small microwave-safe glass bowl, microwave the chocolate on high power for 30 to 35 seconds or until it is a good drizzling consistency. Drizzle the melted chocolate evenly over the squares. Let stand until chocolate is set.