Preheat the oven to 425°F / 218°C and line a muffin pan with 6 paper liners. Set aside.
In a medium-sized bowl whisk together the all-purpose flour, granulated sugar, poppy seeds, baking powder, and salt.
In a separate bowl whisk together the buttermilk, oil, egg, vanilla extract, and almond extract until combined.
Fold the dry ingredients into the wet ingredients with a rubber spatula, and mix just until combined and there are no visible streaks of flour. Your batter should not be all the way smooth, and it's ok if there are still some small chunks in it.
Divide the muffin batter evenly between the 6 muffin cups, filling them to the top of the liner.
If desired, add a generous sprinkle of coarse sugar on the top of each muffin to give them a perfectly crunchy top.
Bake the muffins for 6 minutes at 425°F / 218°C to give the muffins a nice rise and a domed, golden brown top. Then (keeping the muffins in the oven) reduce the oven temperature to 350°F / 175°C. Continue to bake for an additional 20-23 minutes.
While the muffins bake make the almond glaze! Whisk together the powdered sugar, milk, and almond extract in a small bowl until smooth.
Let the muffins sit in the pan for 10 minutes to cool, then move them to a wire rack to finish cooling. Drizzle them with the almond glaze at this point and garnish with coarse sanding sugar, sliced almonds, and/or lemon zest.