I didn't take pics of the process, but I want to share this lemon raspberry cake I made for Kate's baptism.
It's made with two boxes of white cake mix and three nine-inch layers. I made the filling and icing from scratch, but I see absolutely nothing wrong with using a cake mix.
Here's the recipe I used for the raspberry filling. I skipped the raspberry liqueur since liquor isn't sold in grocery stores here and I was not about to make a special trip for two tablespoons of anything!
Once I baked the three layers, I cut the tops off to be as level as possible and slopped on the filling. It becomes a nice gelatin-like texture if you leave it in the fridge long enough. I was afraid it would be a little too thin and turn the buttercream pink around the edges, but it worked very well. If you look at the picture of the cake on that site, you'll see it's better to circle the edges of your layers with icing (imagine outlining the filling on the layer) so it doesn't seep out, but I had to get it filled and stacked the night before I made the icing.
Here are the videos I used for the icing: recipe (plus lemon extract) and smoothing technique. If I'd had more time I would have been more careful and decorated the edges for a crisper look, but it didn't work out that way.
For the cross, I rolled out some premade white fondant and traced a scallop pattern on top of it, then cut it out with a knife. I punched holes in it (a must for the pretty eyelet look!) with a round tip and then made some royal icing to add the detail. Royal icing consists of some meringue powder, a lot of powdered sugar and a little warm water. I don't have the measurements, because I only needed a little bit so I just tossed it together. I tried to do a star scallop around the bottom with the leftover royal icing but it was too warm from being in my hands so it got kind of melty. At that point I just needed to get it done so I could get the rest of the house ready for the big party!
The rose is just a strip of fondant -- maybe 3/4 inch? -- rolled into itself. I did it several times until it turned out right.