Recreating Tonka Bean Gu Cake Last year, Gu released this cake bar, described as

'Dessert with Layers of Milk Chocolate Mousse, Salted Caramel Crémeux, Chocolate and Almond Sponge on a Crisp Praline Base

Irresistible layers of velvety Belgian milk chocolate mousse, tonka bean infused salted caramel crémeux, decadent chocolate and almond sponge on a crisp praline base';

http://www.sainsburys.co.uk/webapp/wcs/stores/servlet/gb/groceries/all-desserts/gu-festive-chocolate-bar-600g?langId=44&amp;storeId=10151&amp;krypto=DxLxtJ%2B5LYoBOqqxg%2FWPKn9DP9qJQdQ0%2BQZAoTgk22lid3miVrBgmgj18A0zAWNeuZwOxESCgt50nzDj9lnJY924GqN2GdPB5Dir9lBiGdcbQTl9nblc9795Xh2BfR9ZU0EFaR1tSKGCHBBF35q%2BfSshwhudCMebv%2F%2B9hDvzB6E%3D&amp;ddkey=http%3Agb%2Fgroceries%2Fall-desserts%2Fgu-festive-chocolate-bar-600g

Which was amasing. However they no longer do it. Does anyone have any experience creating something along these lines? As we were planning to try to recreate this ourselves. Any tips, similar recipies (or indeed a location to buy the original :) ) would be much appreciated!

We are mainly concerned about the 'Cremeux' as we have made similar things to the other components before but can't get a recipe or anything on the Cremeux.

Thanks
In the oven at about 340/350 F, bake high quality/real white chocolate chunks or chips or buttons until evenly but lightly golden brown, moving it around with a wooden spoon or spatula. By doing this, you are caramelizing the sugars in the white chocolate = your caramel component. 

Remove from the oven and place into a container. Heat 35% whipping cream to a simmer and just cover the caramelized white chocolate. Less cream will make a thicker emulsion (more ganache style) and more cream will make a thinner emulsion (spreadable). While hot, add some sea salt or salt of choice. With a hand blender, whizz up the mixture until evenly combined and whipped. 

At this point you could use it as is (may need to heat slightly to use or spread), or you could opt to whip it further for a lighter, more mousse-style finish. 

This filling can be used in macarons, cake layers, thinned out as a sauce, a pudding, etc etc. I highly recommend this.