Combine the blueberries, butter, lemon juice, agave nectar, and vanilla essence in a medium saucepan. Cook over medium-high heat, stirring frequently for about 10 minutes, until the blueberries begin to break down and release their juices, and the mixture thickens slightly. The butter will melt into the berries creating a rich, glossy base. I find that constant stirring prevents the bottom from scorching and helps the flavors blend together more evenly.

Remove the saucepan from heat and stir in the lemon zest and sea salt. Taste the glaze and adjust seasonings if needed—the salt should enhance the blueberry flavor without being noticeable. I like to add the zest after cooking rather than before, as this preserves its bright, fresh citrus aroma. Let the glaze cool for a minute or two before using so it reaches a pourable consistency.

Pour or spoon the warm glaze over your desired food—whether it's pancakes, waffles, cheesecake, or desserts. The glaze will set slightly as it cools, creating a beautiful coating that's both glossy and flavorful.