In a small saucepan, cover the thyme sprigs with the maple syrup and simmer over moderate heat for 1 minute; set aside.
In a large bowl, whisk the flour with the baking powder, table salt and chopped thyme. Cut in the butter until it's pea-size. Make a well in the center and pour in the milk. Stir with a fork until the dough is evenly moistened; turn out onto a lightly floured work surface and gather into a ball.
Roll out the dough 3/4 inch thick. Using a floured 2 3/4-inch round cookie cutter, stamp out the biscuits as close together as possible. Press the scraps together and stamp out more biscuits. Transfer the biscuits to a parchment paper-lined baking sheet and refrigerate for 30 minutes.
Preheat the oven to 400°. Brush the biscuits with the maple glaze and sprinkle with sea salt. Bake in the upper third of the oven for 20 minutes, or until golden. Serve warm.
The recipe can be prepared through Step 3 and refrigerated overnight.