For the Cake, preheat oven to 325°F. Grease bottom and side of 1 (9-inch) round cake pan with no stick cooking spray. Line bottom of pan with parchment paper.
Beat egg whites in medium bowl with electric mixer on high speed until soft peaks form. Beat flour, sugar, sour cream, melted butter, Matcha Blend and baking powder in large bowl with electric mixer on low speed to moisten. Beat on medium speed 2 minutes. Gently stir in egg whites until combined. Pour batter into prepared pan.
Bake 25 to 29 minutes or until toothpick inserted in center comes out clean. Cool cake in pan 10 minutes. Remove from pan; cool completely on wire rack.
For the Frosting, stir sugar into boiling water in large bowl until dissolved; let cool. Add meringue powder to sugar mixture; beat with electric mixer on low speed until just blended. (If using a stand mixer, use the wire whisk attachment.) Beat on high speed until stiff peaks form. Gently stir in marshmallow creme and lemon extract with spatula until smooth.
Slice cake in half horizontally to form 2 thin layers. Place 1 of the layers on serving platter and spread with lemon curd. Top with second cake layer. Frost top and side of cake with the Frosting. Lightly garnish with grated lemon peel, if desired.