Pre-heat oven to 350F (180C). Lightly grease and flour or spray two 7 or 8 inch (18 or 20cm) round cake pans.
In a medium bowl whisk together flour, salt, baking powder and baking soda, set aside.
In a large bowl or stand mixer using the paddle attachment cream the butter and sugar on medium speed until light and fluffy, approximately 2-3 minutes. Add the egg and beat until well combined, add the vanilla and combine well.
In a small bowl mix together the cocoa and green food coloring, add to the creamed mixture and beat well.
Add the dry ingredients alternately to the creamed mixture with the yogurt. Beat to combine, add the milk and combine well. Divide the cake batter evenly between the prepared cake pans.
Bake for approximately 20-25 minutes, test for doneness with a toothpick, if it comes out clean or with a few crumbs attached it is done. Let the cakes cool in pan for about 20 minutes, then move to a wire rack to cool completely before frosting.
FOR THE FROSTING
In a medium bowl beat together the butter and cream cheese on medium-high speed until creamy approximately 1 minute. Lower the speed to medium and add the powdered sugar, 1 cup at a time, beat well after each addition. Add vanilla, cream and or Baileys and beat until fluffy, about 3 minutes. Refrigerate until ready to use.
To frost the cake, place the first layer on a large plate or cake turntable top side down, spread with a layer of frosting, place the second cake top side up and frost the whole cake with remaining frosting. If you wish you can decorate the sides and top of the cake with green sprinkles. Enjoy!
Notes
Take any cold ingredients out of the refrigerator an hour ahead of time or sooner if it’s cool in your kitchen.For homemade cake/pastry flour - for every cup of all purpose flour, remove two tablespoons and replace with two tablespoons of corn starch. Be sure to sift the flour and cornstarch together a couple of times, this way it is sure to be properly combined and lump free.The cake can keep covered unfrosted at room temperature for up to two days. If it is frosted it should be refrigerated. It will last up to four days in the fridge. Just bring it to room temperature (for about an hour or so) before serving.Freeze the frosted cakes in a tightly covered airtight freezer safe container. Or place the cake on a cookie sheet and place in the freezer until the frosting is frozen, then wrap it tightly in plastic wrap or foil, then place in a freezer safe container or bag. The cake will last in the freezer for up to 3 months.Thaw the frosted cake loosely covered at room temperature for 2-3 hours.