Begin by making the raspberry filling. In a small saucepan, whisk together sugar and cornstarch. Add raspberries, lemon juice, and water and toss to coat. Turn on heat to medium.

Crush raspberries as they soften using a potato masher or back of a fork, bring to a simmer. Once pureed and lightly bubbling, cook for about 4-5 minutes or until jam has thickened slightly, stirring occasionally. It will continue to thicken as it cools. Turn off heat and add vanilla. Set aside to cool.

For the cakes, preheat oven to 350F and grease three 8-inch cake pans well. I also add a round piece of parchment paper to the bottom of each to assist in cake removal.

Whisk together flour, cocoa powder, sugar, baking soda, baking powder, and salt in a large bowl.

In a separate bowl, use a hand mixer or stand mixer to beat together oil, eggs, sour cream, milk, and vanilla.

Slowly add the wet ingredients to the dry, continuing to mix the entire time. Once combined, add hot coffee and mix well. The batter will be liquidy and seem thin, this is okay!

Pour cake into three prepared pans and bake for 30-35 minutes or until toothpick inserted in center comes out clean. Let cakes cool for at least 2 hours.

While cakes are cooling, make the buttercream. In a large bowl, using a hand mixer or stand mixer, beat butter and powdered sugar until combined. Add in cocoa powder and mix, then add in milk, salt, and vanilla. Beat until totally creamy and smooth.

Assemble the cakes in layers. Start by trimming off the top of any cakes that have domed slightly. You want the cakes to be as flat as possible. I do this by running a serrated knife horizontal across the top of the cake to make it even.

Add 1/3 of the frosting to a piping bag or quart-sized ziplock bag. Using an icing spatula, add a small bit of chocolate frosting to the bottom of the cake stand to hold cake in place as 'bottom layer' and add the first cake bottom side down.

Pipe on an outside edge around the top of the cake, almost like a dam, so that the jam can go in the center.

Add half of the jam to the center of the first cake and spread until you reach the icing 'dam'.

Using the next layer of cake, flip upside down so that the flat bottom is on top. Place on top of the first layer. Repeat steps 11 + 12, using up the rest of the jam, and then flip the last cake upside down with the flat bottom on top onto the cake as the third layer.

Ice the entire cake with the remaining frosting, with optional piping on top. I like to pipe small icing peaks around the top and add raspberries to every other peak.

Store in fridge up to 3 days ahead and enjoy for 5 days in fridge.