Preheat oven to 325 degrees F. Spray two 8-inch round cake pans with baking spray. Line bottom of each pan with a round of parchment paper, and then spray the parchment with baking spray. Set aside.
Sift together the flour, baking powder, baking soda, and salt in a bowl; set aside.
In the bowl of a stand mixer, beat the pureed avocado and the butter with the sugar until completely combined. Beat in vanilla. Beat in eggs one at a time, mixing well after each addition. With the mixer on low speed, beat in all of the buttermilk until just combined. Add the flour mixture in 3 additions, mixing each addition until just combined. Once all flour is incorporated, increase mixing speed to medium and beat for 20 seconds longer. Be careful to not over mix.
Divide batter among the two prepared cake pans. Bake until golden on top and a wooden pick inserted in center comes out clean, about 25 minutes. Cool cakes in pans on racks for 10 minutes before inverting, removing parchment paper, and cooling completely.
While the cakes are cooling, prepare the frosting.
In the bowl of a stand mixer, cream the pureed avocado with the butter and cream cheese until smooth. With mixer on low speed, gradually add the confectioner’s sugar. Once all the sugar is incorporated, add the lime juice and the vanilla. Add milk, as needed until frosting is light and fluffy. Increase mixing speed to medium and beat for 5 minutes. If frosting is too thin, add a bit more confectioner’s sugar, if too thick adjust by adding a bit more milk.
Place one of the cakes on a plate or platter. Spread the raspberry jam evenly over the surface. Place remaining cake on top. Spread or pipe top and sides of cake with buttercream.