Heat milk and butter in the microwave in a glass or plastic measuring cup or bowl or in a small saucepan, just until butter melts.
Add warmed milk and melted butter, eggs, vanilla, sugar, and salt to blender jar, cover and blend until smooth. Add flour and blend until smooth.
Place a fine-mesh strainer over a large bowl and strain out any lumps.
Heat an 8-inch non-stick skillet or crepe pan over medium heat and lightly coat with butter or cooking spray. For each crepe, pour ¼ cup batter into the center of the skillet and immediately rotate the pan until the batter covers the bottom of the skillet in a thin layer. Cook until light brown and the top begins to dry out, approximately 1 minute. Flip and cook an additional 30 seconds.
Repeating with remaining batter. Stack completed crepes on a plate. (If your crepes are sticking together, put wax paper between the crepes.) You can put crepes in a 200º oven to keep warm until ready to serve.
Spread chocolate spread down the center of each crepe and top with sliced bananas. Roll up and serve with whipped cream and grated chocolate, optional.