I recommend a nonstick pan. Set it on the stove to heat up.
Slice bread into even 3/4 inch thick slices. You can use any type of bread you choose, but don't go for one that has too open of a crumb.
Beat eggs, half and half, whiskey and salt together well.
Break the chocolate bars into pieces, then unwrap at the seal and set aside. ( I find that breaking the chocolate into random pieces works better for arranging them within the contours of the bread crust, than breaking them into their even squares does).
When the pan is hot enough (medium high) add one tablespoon of butter and one teaspoon of olive oil to it.
Place one bread slice into a dish that has low walls but also some depth , and pour egg mixture in the dish, without allowing the mixture to come over the top. Hold it so for 20 to 30 seconds to allow the bread to asbsorb it (the time needed will vary depending on your choice of bread and how dry it is). With a perforated spatula put the slice in the pan, and lower the heat to medium. Repeat with another slice and put it to the side of the first one. When the first one is near done to your liking, begin arranging the chocolate pieces on top, by placing white chocolate over half of it and semisweet chocolate over the other half. Before the chocolate has melted completely, transfer the slice to a prepared plate. Lift the other slice with a spatula and place index finger and middle finger in a "V" shape over the top, then flip it over its chocolate covered sibling, matching the contours.
Carefully place confectionary sugar in a fine strainer, set over a saucer, and dust each toast over the half under which the semisweet chocolate lies. Do the same with the cocoa powder, dusting the half where the white chocolate lies.