In a large bowl, whisk together the eggs and yolks.
In a medium saucepan, heat the milk, cream, granulated sugar, vanilla, dash of cinnamon, and salt over medium heat, whisking occasionally, until the mixture is warm to the touch and the sugar is dissolved, about 3 minutes. Remove the mixture from the heat, and whisking constantly, pour about one quarter of it into the egg mixture. (Note: This step is important. If you do add too much warm milk to the eggs, you’ll make scrambled eggs.)
Pour the egg and milk mixture back to the pot and place back on the heat. Cook until it thickens, about 3 minutes, and then pour through a strainer, removing any clumps. Use immediately, or chill the custard for up to 2 days until ready to use.
Preheat the oven to 200˚F. I like to place a baking sheet in the oven. This is where I like to keep the French toast warm while I make them in batches.
In a large heavy skillet, heat 1 1/2 tablespoons of the butter over medium heat until it is hot but not smoking. Take your challah slices and dip them into the egg/milk mixture, coating them on both sides. I didn’t leave the slices in there too long because I don’t like a gooey French toast. If that’s your thing, then I’d suggest leaving them in there for 2-3 minutes. I did a quick dip.
Add 2 or 3 slices of challah (or as many that can fit in your pan) and cook for 3 minutes on each side, or until puffed and golden brown. Transfer the French toast to a baking sheet and keep it warm in the oven. Repeat with the remaining butter and bread slices.
Top with the macerated strawberries. You can serve it with more butter and maple syrup, if you like!