Use a butter knife to loosen the cake from the pan edges if necessary. Invert onto your cake platter, peel off the parchment paper, and split the cake into two layers. Insert a flexible cutting board between the two layers and lift off the top layer, inverting it cut side up onto another flexible cutting board.
For more detailed instructions and pictures on splitting the cake, see Chantilly Cake Tutorial: Splitting and Frosting Chantilly Cake (Part 6).
Brush half of the guava syrup on the cut side of each cake layer.
Make sure to brush the syrup all the way to the cake edges, or those cake pieces will be a little drier.
These layers should be brushed further to the edges.
Whip the cream in an electric mixer until barely stiff.
Add the ½ c. guava nectar concentrate.
Whip until stiff.
Place one third of the frosting onto the bottom cake layer. Use a small, metal angled spatula to spread frosting evenly out to the edges.
Place the top layer, cut side down, onto the frosted bottom layer.
Working a small section at a time, place some frosting onto the cake top, then push it over the edge and quickly frost the side.
Repeat until all the sides are covered.
Finish smoothing the top last.
Cover and chill for a couple of hours or more to set the frosting.
