This is my daughter's favorite cake, so over time it has become an annual event to make it. The lime curd recipe was improved last year when using Pat Duran's lime curd recipe.... and on that page the picture shows a similar cake to this one!
Follow the directions to make 2 layers of white cake.... in the bottom one fold in a handful of blueberries to give some sweetness from baking.
In a bowl cream the margarine and sugar together. Slowly add eggs one at a time, blending well with each one. Add the lime juice, it may curdle. Transfer to a pot and heat over low mixing until smooth. Once smooth raise the temp to medium and whisk until thickened (170 degrees). Cool off in fridge to continue thickening.
In a pot, add water and mix in gelatin. Turn to low heat for a few moments to dissolve the sugar. Return to room temp. In chilled bowl, pour whipping cream and cooled gelatin mixture and beat on medium 5 minutes. Mix in the powdered sugar and return to medium beating until stiff peaks form (another 5 minutes)
To assemble the cake, take the bottom layer and frost with whipped cream. Pour out most of the lime curd over the frosting and sprinkle with half of the rest of the blueberries. On the bottom of the top layer, frost with whipped cream and then flip over on top of the bottom layer. Frost top with whipped cream and top with what is left of the lime curd. Sprinkle the rest of the blueberries over the cake.
As a side note.... The lime curd makes a great "toxic sludge" when making a young boy's cake :)