Meanwhile, toast the almonds as dark as possible without burning them in a 160°C/320°F oven. Add the hot toasted almonds to the hot cream. Stir. Cover with plastic wrap and let steep for 2 hours.
Reheat the cream and then strain out the almonds. Reheating prevents the almonds from holding on to too much cream when you strain it. There should be about 2.8kg/6lb2.72oz of cream left after straining the almonds out. Add the sugar while the cream is hot so that it dissolves. Cool over an ice water bath and then reserve in the refrigerator until needed.
When you are ready to assemble the cake, whip 700g/ 1lb8.64oz of cream with the stabilizer in the bowl of an electric mixer until stiff. Pour into a piping bag fitted with a #4 fluted piping tip and assemble the cakes.