Put instant coffee and a 50/50 mixture of the two sweeteners in a bowl, jar, or tall glass.
Add boiling water and use a handheld milk frother or a hand mixer to whip the mixture until it's thick and frothy, which will take about two to five minutes. You can also use a whisk, although that will take much longer.
Once you have a thick and frothy texture, you can serve the coffee hot or cold.
To serve it cold, add ice cubes to a large glass, pour milk over the ice, and add a few tablespoons of the whipped coffee.
To serve it hot, pour heated milk into a large glass, enrich it with the whipped coffee, and stir the mixture until you have the desired consistency.