For the Meyer Lemon Buttermilk Cake

1. Spray a cooking oil onto two 9 inch springform pans or three 6 inch springform pans and line the bases with parchment paper. You can either trace the bottom of the springform pan and cut to size or use your already owned 6 or 9 inch cake parchment paper liner.
2. Preheat oven to 350F (177C)
3. In a stand mixer with a paddle attachment (or a large bowl and electric hand mixer), cream together the Butter and Sugar on high speed for 4-5 minutes until mixture becomes smooth.
4. While that is mixing, sift together dry ingredients in a separate bowl: Cake Flour, Baking Soda, Baking Powder, Salt, and set aside. 
5. Once you have successfully creamed your butter and sugar, scrape down the bowl with a rubber spatula and turn mixer on low. Add Eggs, Vanilla, Vegetable Oil and Meyer Lemon Zest and mix until well incorporated.
6. Scrape down bowl again. Slowly add dry ingredients and Buttermilk, alternating back and forth, ending with Flour mix. Mix until smooth, then turn off mixer.
7. Pour an evenly distributed amount of cake batter  into each springform pan.
8. Set pans on your oven’s middle rack and let cook for 25-35 minutes (depending on your oven).
9. Cakes are done when a toothpick comes out dry or they read 210F (99C) on an instant read thermometer. Remove from oven and place all pans on a cooling rack for 10 minutes.
10. Open springform pans and place cakes carefully back on cooling rack until room temperature, or whenever you are planning on constructing your cake.

For the Meyer Lemon Curd

1. Set up a double boiler over medium heat, taking care that the top bowl does not touch the water below. Combine Sugar, Butter, Eggs, Meyer Lemon Zest, Meyer Lemon Juice, and optional pinch of Salt, then whisk together until the curd thickens and coats the back of a spoon (15-25 minutes)
2. Once thickened, strain through a fine mesh sieve into a separate bowl to stop from cooking.

For The Salted Rosemary Buttercream

1. Set fine mesh sieve into a metal stand mixer bowl and set aside. Melt cubed Butter in a medium saucepan over medium-low heat. Add Rosemary Sprigs and bring to a bare simmer, stirring and swirling constantly (2-3 minutes). Take care not to brown the butter. Remove from heat and strain through fine mesh sieve. 
2. Allow to cool until butter is room temperature and solidified (1-2h). Place in fridge wrapped until ready or leave room temp if you are planning to construct the cake that day.
3. In a stand mixer with a paddle attachment (or a large bowl and electric hand mixer), start to cream the butter then add the rest of the ingredients: Powder Sugar, Cream or Milk and Salt until smooth.
4. Transfer some of the mixture to piping bag if you are ready to construct the cake. 

Constructing the Cake

1. On a cake stand or plate, put down a bit of buttercream for stability and then the first layer of cake. 
2. Pipe buttercream on top of the first layer of cake with your piping bag. Smooth buttercream out and pipe a thin circle around the outer edge of the cake Then pour the Meyer Lemon Curd in the middle of the circle with a big serving spoon and use the back of the spoon to evenly distribute. 
3. Repeat until the top layer, then cover your cake and pipe however you would like. Drizzle the honey on with a small spoon or honey dipper. All over the top and making it drip down the sides of the cake. The Honey in my opinion is a very important flavor enhancer and adds dimension. For decoration, add fresh rosemary sprigs or candied meyer lemon, or even edible flowers.