Grease an 8-inch or 9-inch square baking tin, or alternatively, line it with baking parchment to ensure easy removal later. Set the tin aside.

Place the granulated sugar and full-fat milk in a heavy-based saucepan. Set the pan over medium heat and stir gently until all the sugar granules are completely dissolved.

Add the butter to the pan and continue stirring until it fully melts and integrates into the mixture.

Pour in the condensed milk and raise the heat slightly to bring the mixture to a low boil. Stir constantly to prevent any scorching or sticking to the bottom.

Maintain the mixture at a gentle but steady boil over medium-low heat, stirring without pause for about 20 to 25 minutes. It should deepen in color to a rich golden hue and noticeably thicken. If available, monitor the temperature with a candy thermometer—it should reach between 112–115°C (234–240°F), known as the soft-ball stage.

Once the correct temperature and consistency are reached, take the pan off the heat. Add the vanilla essence and let the mixture rest for a couple of minutes.

Begin beating the mixture vigorously with a wooden spoon, or use a stand mixer fitted with a paddle attachment. Continue beating for 5 to 10 minutes until the mixture loses its sheen, becomes thicker, and develops a grainy texture.

Immediately transfer the mixture into the prepared tin, smoothing the surface evenly. Allow the tablet to cool and firm up at room temperature for several hours or overnight.

Once set, cut into even squares and store in an airtight container.