Combine the butter and sugar in the bowl of a stand mixer fitted with a paddle attachment. Cream together until smooth and fluffy, about 3 minutes. Add the eggs one at a time, mixing until incorporated. Mix in the vanilla.
In a separate bowl, whisk together the flour, baking powder, and salt. Alternate adding the dry ingredients and milk to the egg mixture in 3 batches, mixing on medium speed until each batch is really well-incorporated. Scrape down the bowl as needed. Mix in the lemon zest, lemon juice, and poppy seeds.
Spoon the batter into the prepared muffin tin, evenly distributing it. Bake the muffins for 25 minutes, or until set and golden.
Serve warm with a smear of salted butter and a generous drizzle of the lavender honey.
Combine the honey, water, and dried lavender in a small saucepan. Bring to a boil over medium-high heat, allowing the honey to dissolve.
Reduce the heat to low and simmer for about 15 minutes. Turn off the heat and let the honey sit to infuse for 10 more minutes.