Preheat the oven to 350F. Spray a 8.5 x 4.5 or 9 x 5 loaf pan with baking spray. Line the pan with two sheets of parchment paper, making sure the parchment extends over the sides of the pan to form a "sling". Secure the sides with binder clips to secure the parchment in place.
Combine the blueberries and 1 tablespoon of flour together in a small bowl. Toss to coat the blueberries with flour.
1 cup fresh blueberries, 1 tablespoon all purpose flour
In a medium bowl, whisk together the 1 ⅔ cups of flour, baking powder, and salt. Set aside.
1 ⅔ cups all purpose flour, 1 ½ teaspoons baking powder, ¼ teaspoon fine sea salt
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, sugar, lemon zest and thyme on medium-high speed until light and fluffy, about 3-5 minutes.
½ cup unsalted butter, room temperature, 1 cup granulated sugar, 1 tablespoon lemon zest, 1 teaspoon fresh thyme, finely chopped (optional)
Add the eggs one at a time, scraping the bowl after each one has been added. Add the vanilla.
2 large eggs, 1 teaspoon pure vanilla extract
With the mixer on low speed, add the flour mixture to the batter in the three additions, alternating with the milk in two additions, beginning and ending with the flour. Mix until just combined.
½ cup milk, room temperature
Remove the bowl from the mixer and fold in the blueberries.
Pour the batter into the pan and bake 45-55 minutes or until a toothpick stuck in the loaf comes out with few dry crumbs.
Cool the loaf in the pan for 15 minutes on a cooling rack. Remove the loaf from the pan and place on the cooling rack to continue cooling.
In a small bowl, whisk together the confectioner's sugar, lemon juice and heavy cream until thickened and well combined.
1 cup confectioners sugar, 2 tablespoons fresh lemon juice, 1 tablespoon heavy cream
Pour or drizzle the glazes over the warm (not hot) loaf cake. Top with extra blueberries and garnish with fresh thyme. Cool completely before slicing and serving.