Chocolate Cremeux Filling

Mix egg yolks with sugar until well incorporated. Bring heavy cream and milk into simmer and slowly pour into the egg yolk mixture while whisking vigorously. When fully incorporated, transfer the yolk + milk liquid into the pot, whisk until the mixture slightly thickens. Pour the mixture onto the chocolate. Let it soak for 1 min and whisk until well incorporated. Place it in a plastic wrapper and let it sit for 2-3hrs or overnight and then pipe!