To make the cake:
1. Preheat oven to 350 degrees F. Grease pans, then line bottoms with parchment paper.
2. In the bowl of an electric stand mixer, with the paddle attachment, beat the butter and sugar on medium-high speed until light and fluffy.
3. Reduce speed to medium-low, and add the eggs and yolk, one at a time.
4. Mix together the milk and extracts. In a separate container, mix together the remaining dry ingredients. With the mixer on low speed, add 1/3 of the flour mixture, then 1/2 of the milk, then the next 1/3 of flour, then the rest of the milk, then the last of the flour. Remove bowl from mixer, and finish stirring by hand.
5. Spread into the prepared pans. Bake the two 9-inch pans for 25-30 minutes, until springy in center, and just pulling from sides. Bake the sheet pan for 18-20 minutes. Let cool in pans for 10 minutes, then turn out onto wire rack to cool completely.
To make the buttercream:
This is a Swiss meringue buttercream, which is silky smooth and light.
1. Put whites in the clean bowl of an electric mixer. With a clean hand whisk, beat in the sugar. Place bowl onto a pot of low simmering water, not allowing the bottom of the bowl to touch the water. Stir the mixture frequently with the whisk, to melt the sugar completely, but not to aerate. Watch that the egg whites don't begin cooking — keep the water low, and stir very often. When it appears that the sugar is melted, dip your forefinger and thumb into the whites and rub your fingers together to check for undissolved sugar. If the mixture is silky smooth, check the temperature by dipping a finger deep into the mixture, near the bottom of the bowl. If it is too hot to keep your finger in, it's ready!
2. Transfer bowl to the mixer, with the whip attachment, and whip on med-high speed until stiff peaks form. (This is your Swiss Meringue, which can be used alone as a frosting or pie topping.) Continue on for buttercream:
3. On medium-high speed, add the soft butter, one stick at a time, one after the other. Add the extract and whip until incorporated. The mixture should be smooth and silky at this point. Use at this point, or refrigerate, or freeze. Allow to come to a soft room temperature, and re-whip before icing the cake. (Any leftover buttercream can be frozen up to 3 months.)
To make the TODAY Sunrise Cake:
You will need:
—Two 9-inch-by-12-inch cookie sheets with sides, prepared as directed.
—One 11-inch-by-17-inch cookie sheet with sides, prepared as directed.
—One small ovenproof bowl, about 3 inches in diameter, and 2 to 3 inches deep, lightly greased.
—2 batches of vanilla cake batter
—1 batch of vanilla buttercream
—1 small bottle each of gel food colorings in magenta, red, orange, egg yellow.
1. Make 1 batch of cake batter and divide in half. Add a couple drops of red gel coloring to one half, and orange to the other, stirring in well. Add enough color to match the respective arcs of the TODAY sunrise. Pour each color into a prepared 9-by-12-inch cookie sheet, and bake for 12-15 minutes. Cool briefly, then turn out onto a wire rack and remove parchment to cool completely.
2. Make second batch of cake batter and transfer 1 1/2 cups to another bowl. Stir magenta gel coloring into this portion until the desired color is reached. Transfer to the prepared ovenproof bowl and bake 10-12 minutes, until the top springs back. Invert over a wire rack and let cake mound gently release. Remove bowl. To the larger portion of batter, stir in egg yellow coloring. Transfer to the prepared 11-inch-by-17-inch cookie sheet, and bake 15-17 minutes. Cool as directed.
3. Remove three 1/2-cup portions and one 1/4-cup portion of buttercream to separate bowls. Color the 1/4-cup magenta, and each of the remaining 3 portions one of the sunrise colors of red, orange, egg yellow. Set aside along with the plain, uncolored buttercream until ready to assemble.
1. Place the magenta cake mound onto a serving platter, flat side down. Spread a thin layer of magenta buttercream over the outside to smooth any rough surfaces or crumbs. Place into the freezer for 10 minutes. Remove from freezer and spread an even layer of plain buttercream over the outside, about 1/8-inch thick. Return to freezer for 10 minutes.
2. Meanwhile, cut the red cake sheet into triangles — the length of the bottom to the tip should be equal to the length from the bottom of the cake mound to the center point at the top. Remove the mound from the freezer, and press the triangles around the mound, the tips meeting at the top. If there are spaces that aren’t covered by cake, cut the remaining pieces to fit and insert them as needed. The sections of cake should be tightly wedged together. Spread a thin layer of matching red buttercream over the outside to smooth the surface of the mound. Place into the freezer for 10 minutes. Spread an even layer of plain buttercream over the outside, about 1/8-inch thick and return to freezer for 10-15 minutes.
3. Repeat with the orange layer of cake and orange buttercream, freeze 10 minutes then apply the plain buttercream and freeze again.
4. Repeat with the egg yellow cake and buttercream, freeze 10 minutes, then apply the plain buttercream and freeze to set. (Cake can be wrapped and stored in the refrigerator up to 2 days before serving. Refrigerate remaining plain buttercream as well.) Or finish as below and serve same-day.
If buttercream has been refrigerated, soften and whip until smooth. Spread generously over the cake in any style or pattern desired. Slice into wedges and serve!