Preheat oven to 350˚F (180˚C). Line a baking sheet with parchment or lightly grease.
In a medium bowl, whisk together the flour, matcha, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or a large bowl, beat together the butter and sugar until light and fluffy.
Beat in the eggs, one at a time, followed by the vanilla extract.
Add the flour mixture and beat just until combined with no streaks of flour remaining.
Fold in the almonds until evenly distributed.
On the prepared baking sheet, form the dough into a 15 inch (38 centimeter) long log, about 1/2 inch (1.25 centimeters) thick and 4 1/2 (11 centimeters) inches wide.
Bake in the preheated oven until firm and golden on the bottom, 25-30 minutes. Remove from the oven and allow to cool for 20 minutes, until able to be handled.
Reduce oven temperature to 325˚F (165˚C).
Use a sharp, serrated knife to cut the cooled log slightly on the diagonal into 1/2 inch (1.25 centimeter) thick slices.
Arrange the slices back on the baking sheet in a single layer, cut side down.
Bake until the almonds are lightly golden and the texture is crisp, about 20 minutes.
Allow to cool to room temperature before storing in an airtight container for up to 2 weeks.