Fill Pyrex batter bowl (my preference) or 2-quart glass container with milk.
Heat in microwave until bubbles begin to appear around the edge. Temperature should reach 175-180 degrees Fahrenheit after you stir it. (In my microwave, it takes 17 minutes on HIGH).
If a skin forms, remove it.
Allow milk to cool until temperature drops to between 110 and 120 degrees.
Whisk in 1 tablespoon yogurt as a starter You may use yogurt from a previous batch of your own homemade yogurt.
Cover milk and place in a warm environment where the temperature stays around 100 degrees. Allow to incubate for 5-12 hours.
At this point you could chill the yogurt and eat as is. It is your choice to pour off the whey or stir it back in. Straining makes the yogurt thicker and less tart resulting in Greek yogurt.
From regular yogurt to Greek yogurt:
Very carefully pour yogurt into a bouillon strainer aka chinois. If the mesh is fine enough, you won't need to use a cheesecloth or paper towel.
Let yogurt sit in the strainer till the yogurt is reduced by approximately half. Time will vary according to the thickness of the yogurt out of the oven and your own preference regarding texture and sourness. Tip the strainer or stir very gently if whey has pooled on top while straining.
Empty whey from batter bowl and pour yogurt out of strainer back into the original bowl. Use a good whisk to beat until smooth. Add milk if yogurt is too thick along with any sugar or sweeteners you prefer.
May substitute with your favorite milk.
Can use commercial or your own homemade yogurt.
Makes 1 quart (1 quart = 4 servings at 1 cup or 8 servings at 1/2 cup)
Have fun with toppings! Granola, berries, honey, maple syrup, etc.