In a small measuring cup or mixing glass, combine the cola syrup (or neutral cola base) with cherry syrup, prune concentrate (if using), vanilla extract, almond extract, molasses, caramel color or burnt sugar syrup, citrus oil drops, and citric acid (or lemon juice). Stir thoroughly until homogeneous. If using granulated sugar instead of simple syrup, dissolve sugar into 1 tablespoon of a small amount of warm water first and then add to the mix.

Sweetness adjustment

Taste a small 1/2 teaspoon of the concentrated mixture (it will be strong). Adjust sweetness with additional simple syrup or sugar if needed, and adjust acidity with an extra small pinch of citric acid or a few drops of lemon juice. If cherry or prune notes need boosting, add another 1/8–1/4 fl oz of the respective syrup.

Combine with carbonated water

Pour about 12 fl oz of very cold carbonated water into the chilled glass (or a large mixing beaker). Gently pour the prepared flavor concentrate into the carbonated water — pour slowly down the side of the glass to preserve carbonation. Stir gently once with a long spoon or bar spoon to evenly distribute flavor without losing fizz.

Final taste check

Taste and make final adjustments: a touch more citric acid for brightness, a drop more vanilla for warmth, or a tiny extra pinch of molasses for depth. Stir gently after any additions.

Garnish & Serve

Fill the chilled glass with fresh ice if you haven't already. Pour the mixed Dr Pepper over the ice. Garnish with a maraschino or fresh cherry on top or on a skewer. Serve immediately with a straw.