Preheat oven to 350°F. Line a 9×13-inch baking pan with parchment paper. Coat with nonstick spray and set aside.

In the bowl of your stand mixer fitted with the paddle attachment, mix the butter and sugar until creamy. Add the dry pudding mix, eggs, almond extract, vanilla extract, salt, baking soda, and cornstarch. Mix for 1 minute until combined, scraping sides as needed. Add flour and mix until just combined.

Spread the batter into the prepared pan and bake for 20 minutes until lightly golden. Cool on a wire rack.

For the frosting, beat the butter and cream cheese on medium until smooth. Add almond extract and powdered sugar; beat for 30 seconds, then increase to medium and beat for 1 minute until fluffy.

Spread the frosting over cooled bars and garnish with chopped pistachios.

Cut into bars and serve.