1-First Step: Gather and Prep Ingredients Start with mise en place. Measure 2 cups whole milk, 1 1/2 cups granulated sugar, 2 tablespoons butter, and 1/4 teaspoon vanilla extract. Use a heavy-bottomed saucepan (at least 2-quart) to avoid burning. Room-temperature milk blends faster. For vegan, prepare coconut milk now. This setup takes 5 minutes and ensures smooth sailing.

2-Second Step: Combine Milk and Sugar Pour milk into the pot over medium heat. Add sugar gradually while stirring with a wooden spoon until fully dissolved, about 5 minutes. Bubbles form gently; do not boil yet. This dissolves crystals for even sweetness. Taste-test: adjust sugar slightly for less intense homemade condensed milk. Low-calorie tip: use 1 cup sugar here.

3-Third Step: Simmer and Reduce Lower heat to medium-low. Add butter, stirring until melted. Simmer uncovered, stirring every 5 minutes to prevent skin formation. Volume reduces by half in 30-40 minutes. Scrape sides and bottom often. Color shifts to pale gold. Patience pays off for that signature thickness. Altitude note: add 5-10 extra minutes above 3,000 feet.

4-Fourth Step: Thicken and Flavor After 45 minutes, mixture thickens to coat spoon. Test by dropping a bit in cold water; it forms a soft ball. Stir in vanilla. Cook 5 more minutes, stirring constantly. Remove from heat. Cool 10 minutes, stirring occasionally. Vegan version thickens faster with coconut milk.

5-Fifth Step: Cool and Store Transfer to a glass jar. Cool fully at room temp (30 minutes), then refrigerate. It firms up overnight. Label with date. Use in creamy flan recipes right away.