1. Preheat oven to 325° Fahrenheit.
2. Spray a loaf pan with non-stick cooking spray and line with parchment paper. Set aside.
3. In a medium-sized bowl, whisk together flour, cocoa powder, salt, baking soda, and baking powder. Set aside.
4. Using a stand mixer or a large bowl and a hand mixer, cream butter until it is light in color and fluffy. Add sugar and mix very well to combine, scraping down the sides as needed. Mix for at least five minutes until the mixture is pale yellow in color.
5. Add eggs, one at a time, beating well after each addition. Add orange extract and mix to combine. Add the dry ingredients to the wet ingredients and mix until just combined. While the mixer is running, slowly pour in the milk and mix until just combined.
6. Pour the batter into the prepared pan and bake for 60-70 minutes until a toothpick inserted into the center comes out clean. The toothpick may have a few crumbs on it but it shouldn't have wet batter on it.
7. Remove cake and transfer to a wire rack to cool completely.
8. When cool, make the frosting.
9. Using a stand mixer or a large bowl and a hand mixer, cream together butter, powdered sugar, cocoa powder, and salt, scraping down the sides as needed.
10. Add milk and vanilla extract and beat until very smooth.
11. Spread frosting on top of cake and top with orange zest, if desired.
12. Enjoy!

Recipe Tips:

The cake can be made a day in advance and frosted before serving. It's very important that the butter, eggs, and milk are all at room temperature or they will not mix properly.