Preheat oven to 350°F. Lightly grease a 9x13-inch baking pan with baking spray and line it with parchment paper, leaving enough excess to hang over the sides.

In a medium bowl, whisk together flour, baking soda, and salt.

In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar together until light and fluffy, 2 to 3 minutes. Add the eggs, one at a time, scraping down the bowl between additions, and beat each until fully combined. Beat in the vanilla.

Add the flour mixture and beat on low speed until just combined, stopping to scrape down the sides once during mixing. Spread the dough in an even layer into the prepared pan.

Bake for 20 to 25 minutes, or until lightly golden brown around the edges, and a toothpick comes out clean. Let the cookie slab cool completely in the pan before removing it.

In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, beat the butter and powdered sugar together on low speed until powder sugar is combined, stopping to scrape down sides as needed. Increase the speed to medium and slowly pour in the heavy cream, vanilla, and salt, beating until the frosting is light and fluffy, about 1 minute. Add food coloring, if desired, and beat until evenly colored.

Spread the frosting in an even layer on top of the cooled cookie slab. Top with sprinkles, and chill for 15 minutes before cutting and serving.