Place the strawberries in a saucepan over medium heat. Stir occasionally until the mixture starts bubbling. Lower the heat and cook for 15-20 minutes, stirring from time to time to avoid burning. The mixture should thicken significantly.
Remove from the heat and let cool. Puree in a food processor until smooth.
Let the puree cool until room temperature before using it for the cake layers. You can also keep it in the fridge for up to a week.
Preheat the oven to 180º C/ 350º F. Grease two 7 inch/ 18 cm baking pans and line them with circles of parchment paper.
In a mixing bowl combine all-purpose flour, baking powder, salt and sugar. Mix very well.
Add the eggs and keep whisking. Add also the sour cream, vanilla and strawberry puree. Use a rubber spatula to mix gently the ingredients, until combined. Don't overmix but make sure there are no dry ingredients accumulated on the bottom of the bowl.
Divide the batter between the two pans. Bake for about 25-30 minutes or until a toothpick inserted in the centres comes out clean.
Let the cake bases cool until room temperature, before assembling the cake. Alternatively refrigerate them overnight so it is easier to cut each one in two.
In a large mixing bowl beat together the cream, the cream cheese (both cold) and vanilla until thick and fluffy. Let the mixture stay at room temperature while melting the chocolate.
Chop or break the chocolate and put it in a heatproof bowl. Place the bowl over a pan with gently simmering water so the bowl doesn't touch the water (double boiler).
Mix the chocolate with dry spatula or spoon until melted completely (if 1-2 small pieces are remaining this is ok).
Remove the bowl from the heat and keep stirring gently with the spatula 5-10 minutes so it cools down.
Transfer about 1 tablespoon of the cream cheese mixture to the melted chocolate. Whisk energetically to combine until smooth. Repeat 3-4 more times, until the resulting mixture is almost at room temperature.
Gently fold the chocolate into the rest of the cream cheese with the rubber spatula. Mix gently, until the frosting becomes uniform.
Using a long serrated knife divide the cake bases into two equal layers.
Place one layer on a serving plate and spread generously frosting on top (a bit less than ¼ of it). Continue the process until using all layers.
Frost the cake all around with the remaining frosting (about ⅓ of the whole).
Refrigerate the cake for at least 4 hours or overnight.
Decorate with fresh strawberries before serving. You can reserve 1-2 tablespoon of the strawberry puree to make drips.
Make sure that both the cream and the cream cheese are cold before whipping them together.
You can use cake ring when assembling the cake so it looks more even.
If you want to pipe on top of the cake, you need some extra frosting: increase the ingredients with about 30%. Refrigerate the frosting for 30-60 min before piping.