Ingredients

Cake
• By Sally's Baking Addiction
• 1 cup (230g) unsalted butter, softened to room temperature
• 1 and 1/4 cups (250g) granulated sugar
• 1/2 cup (100g) light brown sugar
• 4 large eggs, at room temperature*
• 1 Tablespoon vanilla extract
• 3 cups (375g) all-purpose flour, careful not to overmeasure*
• 1 Tablespoon baking powder
• 1/2 teaspoon salt
• 1 cup (240ml) buttermilk*
• zest + juice of 3 medium lemons*
• 1 and 1/2 cups blueberries, fresh (258g) or non-thawed frozen (275g)
• 1 Tablespoon all-purpose flour
Frosting
• By Sweetapolita
• 1 cup (2 sticks)(227 g) unsalted butter, softened
• 2 teaspoons (10 ml) lemon zest
• 5 cups (625 g) icing sugar, sifted
• 2 tablespoons (30 ml) fresh lemon juice
• 1/4 cup (60 ml) whipping cream (35% cream)
• 1/4 teaspoon (1.25) pure lemon extract
• a pinch of salt
• yellow food gel, optional
Lemon Curd
• *loosely adapted from Williams Sonoma
• Yield: ~ 1-3/4 cups
• 4 lemons (or 6 Meyer lemons), or 2 oranges, or 5 limes (or 8 Key Limes), preferably organic
• 2 whole eggs plus 4 egg yolks
• 1 cup sugar (200 grams) (7 ounces)
• 4 tablespoons (60 grams) (2 ounces) unsalted butter, at room temperature and cut into small even cubes

Instructions

Cake
1. Preheat the oven to 350F. Spray three 8x2 inch cake pans with nonstick spray. Set aside.
2. Make the cake. Using a handheld or stand mixer with a paddle attachment, beat the butter on high until creamy - about 1 minute. Add granulated and brown sugars and beat on medium-high speed until creamed, about 2-3 minutes. Scrape down the sides and bottom of the bowl as needed. Add eggs and vanilla. Beat on medium speed until everything is combined, about 2 full minutes. Scrape down the sides and bottom of the bowl as needed. Set aside.
3. In a large sized bowl, toss together the flour, baking powder, and salt. Slowly add the dry ingredients to the wet ingredients. Beat on low speed for 5 seconds, then add the milk, lemon zest, and lemon juice. Remove from the mixer and stir lightly until everything is just combined. Toss the blueberries in 1 Tablespoon of flour and fold into the batter. Batter is extremely thick. Do not overmix at any point. Overmixing will lend a tough, dense textured crumb.
4. Spoon batter evenly into 3 prepared cake pans. Bake for about 21-26 minutes or until a toothpick inserted in the center comes out clean. Remove from the oven and allow to cool completely before frosting.
Frosting
5. Cream butter and lemon zest in bowl of electric mixer fitted with paddle attachment, about 3 minutes. Slowly add icing sugar, mixing on low speed for about 2 minutes.
6. Add remaining ingredients and beat on med-high for 3-4 minutes until very fluffy. If using color gel, add a drop or two , then beat until blended.
Lemon Curd
7. 1. Wash citrus really well (with a bristled brush under cold water) and using a Zester, remove all of the coloured portion of the peel from the fruit (not the white pith–it’s bitter!) into a bowl or onto a piece of wax paper.If you don't have a zester, you can use the small side of a cheese grater. Rotate fruit as necessary to get as much of the zest off. Repeat until you have 2 teaspoons (30 mL) of the zest, and set aside.
8. 2. Slice the citrus in half crosswise (I find room temperature citrus is best for juicing) using a sharp knife, and extract as much of the juice as you can using a citrus reamer, or I use a small Citrus Juicer. Just be sure to catch all of the juice in a bowl and to completely strain the seeds before using. Repeat the juicing until you have 2/3 cup (5 fl oz/160 mL) of the strained juice.
9. 3. Get your double boiler ready by filling a saucepan with 1? of water, then placing a metal bowl on top of the saucepan. You will need to ensure the bowl fits snugly into the top of the saucepan and that the bottom of the bowl doesn’t touch the water (important, or your eggs will cook!). You can now remove the bowl and continue with making the curd.
10. 4. Whisk the juice, whole eggs, egg yolks and sugar in the bowl until smooth. Add the butter cubes to the bowl, but don’t stir.
11. 5. Heat the water in the saucepan over low heat until it simmers (not boils) and place the bowl atop the rim. Stirring gently, but constantly, using heatproof spatula or wooden spoon, cook until the curd has thickened and all of the butter has melted and is incorporated, about 10 minutes (this can vary). To test if the curd is thick enough, remove the spatula or spoon from the curd and check that it’s coated.
12. 6. Strain the curd over a bowl using a fine-mesh sieve and then stir in the zest. Cover with plastic wrap pressed directly against the curd (to prevent a skin from forming) and chill for at least 3 hours (I like to chill it overnight). It also thickens up a bit more while chilling.
Assembly of cake
13. Spread thin dollop of frosting on an 8-inch thin cake board or cake plate. Transfer 1 cake layer to board, face up.
14. Create a dam around the perimeter of the layer using frosting in a pastry bag fitted with a coupler, then spread lemon curd (apprx 1 cup) inside the dam--this prevents the curd from reaching out over edges.
15. Top with second layer, face-up; repeat frosting around perimeter and lemon curd filling.
16. Top with third cake layer, face-down (brown smooth side up). Spread thin layer (crumb coat) of over top and sides of cake, using offset palette knife and bench scraper for smooth finish. Place cake in refrigerator for about 30 mins to chill.
17. from refrigerator and using same method, frost cake with generous layer of frosting, smoothing again.