2 (15¼-oz.) pkg. lemon cake mix (plus ingredients listed on box for preparing cake)
Baking spray with flour
1/3 cup heavy whipping cream
¼ ounce thyme sprigs (about 1 handful
2 cups (1 lb.) unsalted butter
1 (2-lb.) pkg. powdered sugar
¼ cup fresh lemon juice (from 1 large lemon)
Yellow food coloring gel
White sugar pearl sprinkles
Instructions:
Preheat oven to 350°F. Prepare lemon cake mix according to package directions. Divide batter evenly among 3 (9-inch) round cake pans coated with baking spray.
Bake in preheated oven until a wooden pick inserted in centers of cakes comes out clean, about 25 minutes. Cool in pans 10 minutes. Invert cakes onto wire racks; cool completely, about 45 minutes.
Heat cream in a small saucepan over medium until just simmering. Add thyme sprigs, pressing down using a spoon to submerge. Remove from heat; cover and let stand until cream has cooled, about 1 hour. Remove and discard sprigs. Set aside cream.
Beat butter in bowl of a stand mixer fitted with a paddle attachment on medium speed until smooth, about 2 minutes. With mixer on low speed, gradually add powdered sugar, lemon juice, and infused cream. Increase speed to medium-high, and beat until fluffy, about 3 minutes. (You will have about 7 cups frosting.)
Measure 1¼ cups frosting into each of 2 small bowls. (Reserve remaining undyed frosting in mixer bowl.) Add 4 drops food coloring to 1 small bowl of frosting, and stir to combine. Add 2 drops food coloring to remaining small bowl of frosting; stir to combine. Spoon ⅔ cup each of dark yellow frosting, light yellow frosting, and undyed frosting into 3 separate piping bags. Snip a 1-inch tip off of each bag. Spoon remaining dark and light yellow frostings (about ½ cup each) and ½ cup undyed frosting into 3 separate piping bags fitted with different star tips (such as Wilton 21, 32, and 2D). Set aside all piping bags.
Place a cake plate on a lazy Susan or stand. Put 1 cake layer on plate; spread 1 cup undyed frosting in a smooth layer over the top. Repeat with remaining 2 cake layers and 2 cups of the undyed frosting. Using a bench scraper or a large offset spatula, spread remaining undyed frosting (about ⅓ cup) in a thin layer over sides of cake. Remove cake plate with cake from lazy Susan. Chill until frosting sets and firms up, about 30 minutes.
Return cake plate with cake to lazy Susan. Using the dark yellow frosting in the piping bag with the snipped tip, start at the base of the cake, and turn cake while piping a straight line, creating a ring of frosting around the cake. Leaving space above the dark yellow line, repeat the piping process using light yellow frosting. Repeat with undyed frosting. (Alternatively, leave less space between the rings and repeat series of dark yellow, light yellow, and undyed lines to make more stripes.) Turn cake while dragging the straight edge of a bench scraper (or a large offset spatula) around side of cake (holding scraper at a 30-degree angle toward cake), smoothing and pressing the frosting lines together to create blended stripes of frosting around cake.
Using the reserved dark yellow, light yellow, and undyed frosting in piping bags with star tips, pipe small rosettes and flowers on top of cake. Garnish with sugar pearl sprinkles.
