Grease a sheet pan (about 12x17) and set aside. In a large bowl, cream butter and sugar on medium speed. Add eggs one at a time. Then scrape down sides of bowl and add both vanilla and almond extract; mix well.
In a medium bowl, whisk together salt, baking soda, and flour. Then slowly add to the butter/sugar mixture until just combined.
Press dough evenly into the prepared sheet pan. Bake at 375° for 15 minutes or until very lightly golden. Remove from oven and set aside to cool.
For the buttercream
Beat softened butter on medium speed with an electric mixer or stand mixer. Beat for 3 minutes until smooth and creamy.
Add powdered sugar, cream, and vanilla extract with the mixer running on low. Increase to high speed and beat for 3 minutes. If the frosting is too thick, you can add a little more cream. Just add one tablespoon at a time, then mix thoroughly until you get the consistency you like.
Add green food coloring gel until you get the color you like. Add a little bit of yellow food coloring gel if you want to. Frost the giant cookie once cooled by plopping it all on. Spread it evenly and top with St Patrick's Day green sprinkles. Cut into squares, serve, and enjoy! Store covered at room temperature for 24 hours, then in the refrigerator for up to 5 days.
Video
Notes
For the frosting, if you don't have heavy cream, you can use milk or water instead. If using milk or water, I would try 3 tablespoons instead of ¼ cup. If it's too thick, add another tablespoon.