Dark Chocolate Matzo Brittle

Name: Dark Chocolate Matzo Brittle
Ingredients: 5 unsalted matzos; 10 tbsp. unsalted butter, plus more for greasing; 1 cup sugar; 1 cup light brown sugar; 1 tbsp. kosher salt; 1 tsp. vanilla extract; 1⁄4 tsp. baking soda; 10 oz. semi-sweet chocolate, finely chopped; 1⁄3 cup pistachios (optional), toasted and roughly chopped, for garnish; Flake sea salt (optional), for garnish