Begin by gathering all your ingredients and setting your butter out to reach room temperature - this will take about 30 minutes. Meanwhile, preheat your oven to 180°C (350°F) and line your mini muffin tin with paper cups.
Once your butter is softened, cream it together with the brown sugar using an electric mixer on medium speed. Keep mixing for 3-4 minutes until the mixture becomes light and fluffy. It should look pale and creamy when ready.
Break your eggs into the mixture one at a time, beating well after each addition. Pour in your condensed milk and vanilla extract, then mix everything until well combined. The mixture should look smooth and uniform.
Now add your desiccated coconut gradually, using a rubber spatula to fold it in. Keep folding until all the coconut is evenly distributed throughout the batter. The mixture should be thick but still easy to spoon.
Fill each paper-lined muffin cup about two-thirds full with your batter. Gently tap the filled muffin tin on your counter twice to remove any air bubbles.
Place the tin in your preheated oven and bake for 25-30 minutes. You're looking for golden-brown tops - this tells you they're done. Halfway through baking, rotate the pan to ensure even browning.
When done, remove from the oven and let the macaroons cool in the tin for 5 minutes. Then carefully transfer them to a wire rack to cool completely, which takes about 20-30 minutes. They should feel firm when touched but still have a soft center.
To store, place in an airtight container. They'll keep at room temperature for up to 5 days, or in the refrigerator for up to 2 weeks. You can also freeze them for up to 3 months - just thaw overnight in the refrigerator when ready to eat.
Remember: perfectly baked macaroons should have a light golden-brown color on top, be slightly crisp on the outside, and remain moist and tender on the inside. Don't worry if your first batch isn't perfect - each time you make them, you'll get better at knowing exactly when they're done in your oven.