Combine the granulated sugar and brown sugar with 1/4 cup of the carbonated water in a small saucepan. Warm over low heat, stirring constantly, just until the sugars dissolve completely. Do not boil. Remove from heat and allow to cool slightly.

Once cooled to warm (not hot), whisk in the remaining 1 3/4 cups carbonated water gently to avoid losing too much carbonation. Set aside.

Flavoring Concentrate

Prepare flavor blend

In a small bowl or measuring cup, combine the cola or vanilla extract, almond extract, cherry syrup, orange zest (or extract), fresh lemon juice, grated ginger (or ginger syrup), nutmeg, allspice, and vanilla bean paste if using. Stir vigorously until evenly combined.

Taste a small teaspoon of the concentrate mixed with a teaspoon of the syrup base to check balance. Adjust cherry, lemon, or almond extracts in 1/8 tsp increments if needed — the goal is a complex, fruity, lightly spiced profile reminiscent of Dr. Pepper.

If you prefer a smoother, clearer soda, strain the flavor concentrate through a fine mesh sieve or coffee filter to remove any solids (grated ginger, zest bits).

Stir the flavoring concentrate into the prepared soda base until fully incorporated. Chill the mixture in the refrigerator for 20–30 minutes to let flavors marry.

Finishing & Serving

Fill a tall glass with ice (about 1 cup). Pour 1/2 cup of the flavored soda mixture into the glass.

Top with 1/2 cup chilled club soda or seltzer to add sparkle and adjust sweetness. Stir gently to combine.

Garnish with a maraschino cherry and a slice of lemon if desired. Serve immediately.

Store any leftover flavored soda mixture in a sealed bottle in the refrigerator for up to 3 days. Re-carbonate with chilled club soda when serving to regain fizz.