Preheat oven to 350 degrees. Using the 2 Tbsp. of butter, grease the bottom and sides of a 9x13 baking dish generously. Then dust the bottom and sides of the pan with the 2 Tbsp. of flour.
Cream the butter and sugar together in a stand mixer or with a handheld electric mixer. Add the eggs one at a time, waiting until fully incorporated before adding the next egg. Blend in the orange extract.
In a separate bowl, whisk together the flour, baking powder and salt. With the mixer on low speed, slowly add the dry ingredients into the wet ingredients. Add the milk and beat until smooth. Bake for 30-35 minutes. Let cool for at least 30 minutes.
While the cake is cooling, whisk all the glaze ingredients together in a large bowl. Using a fork or toothpick, carefully puncture the surface of the cake all over. Pour the glaze over the cake evenly. It will look like the liquid is just sitting on top of the cake - don't worry, it will absorb in. Allow the cake to sit at room temperature for 30 minutes, then cover with plastic wrap and refrigerate at least 2 hours.
Before serving, make the cream - beat the heavy cream on high speed of an electric mixer until it starts to thicken. Add the confectioners' sugar and continue to beat until the cream forms stiff peaks. Fold in the orange zest with a flexible spatula. Top each slice of cake with some cream and serve.