Make the Lemon Curd - In a saucepan, beat the eggs and sugar, then stir in the lemon juice, butter, and lemon zest. Cook the mixture over medium-low heat for 15 minutes or until the mixture is thickened and reaches 160 degrees Fahrenheit, stirring regularly. Allow the lemon curd to cool for 10 minutes, then cover and chill for 1-1/2 hours or until it is thick.
Preheat Oven, Prepare Pans, and Make Gelatin - Preheat the oven to 350 degrees Fahrenheit. Grease and flour the three 9-inch round cake pans. Next, dissolve the gelatin in boiling water, then set it aside to cool.
Cream the Butter, Oil, and Sugar - In a large bowl with an electric mixer, cream the butter, oil, and 1 1/2 cups of sugar. Beat the mixture until smooth, approximately five minutes. After, add the eggs in one at a time, beating well after each addition. Then, beat in gelatin mixture, lemon juice, lemon zest, lemon extract, and vanilla extract into the mixture until smooth.
Combine the Dry Ingredients - Мix together the flour, baking powder, and salt иn a medium bowl. Add to the butter mixture, alternating with adding the milk, beating after each addition.
Bake the Cake - Pour the batter equally into the three prepared cake pans. Bake the cakes for 20-25 minutes, or until a toothpick inserted into the middle comes out clean.
Add the Lemonade Mix - In a microwave-safe bowl, add the lemonade concentrate and remaining sugar. Microwave for two minutes on high, uncovered, or until the sugar dissolves, stirring occasionally. Use a fork to poke holes into the cakes and pour the lemonade mixture over the cakes.
Cool the cakes in the pans for 10 minutes. Then, move them to the wire racks to cool.
Make the Buttercream Frosting - Beat the cream cheese and butter until fluffy in a large bowl with an electric mixer. Next, add the confectioners’ sugar, lemon juice, lemon zest, and vanilla. Beat the mixture until well combined.
Assemble the Cake - Place one layer of cake on a serving plate and add 6 tablespoons of raspberry jam, spreading evenly. Add the next layer followed by more raspberry jam. Then, add the final layer and top with 1/2 cup of lemon curd.
Decorate the rest of the cake with buttercream frosting. If desired, add raspberries to the top. Chill for one hour before serving.