Cake
2 eggs
1 1/4 cups sugar
3/4 cup flour
6 tablespoons melted butter
3 ounces melted unsweetened chocolate
1/2 teaspoon vanilla extract
1/8 teaspoon salt
Peanut Butter Layer
3/4 cup creamy peanut butter
1/4 cup softened butter
1/4 teaspoon vanilla extract
3/4 cup powdered sugar
Ganache
2 cups semi-sweet chocolate chips
1 cup heavy whipping cream
1/3 cup peanut butter and milk chocolate chips

Cake
Heat oven to 350ºF. Grease 9 inch round cake pan. Line bottom of pan with parchment paper; grease paper. Combine eggs and sugar in large bowl. Stir in flour, melted butter, unsweetened chocolate, vanilla extract and salt till smooth. Pour into prepared pan. Bake 25 minutes till a wooden pick inserted in the middle comes out clean. Cool on rack for 5 minutes. Run knife around edge of cake; cool for an additional 10 minutes. Invert cake onto serving platter. Remove pan and parchment and cool completely.
Peanut Butter Layer
Beat peanut butter, butter and vanilla extract together till combined. Gradually beat in powdered sugar. Spread mixture on cake. Refrigerate for 30 minutes.
Ganache
Heat cream in small saucepan to boiling; remove from heat. Add semi-sweet chips and let stand 5 minutes. Stir till smooth. Chill 30 minutes till mixture is spreadable. Spread chocolate on top and sides of cake. Melt peanut butter & milk chocolate chips in resealable plastic bag on 70% power for 30 seconds. Knead bag to mix. If necessary, microwave at additional 10- to 15-second intervals till melted. Cut a small hole from corner of bag; squeeze to drizzle over cake. Store in refrigerator. Let stand for 30 minutes before serving.