1 1/2 teaspoons active dry yeast (from one 1/4-ounce envelope)
1 1/2 cups all-purpose flour, plus more for surface
1 tablespoon granulated sugar
1 teaspoon cinnamon
1/4 teaspoon salt
1 large egg, lightly beaten
1/2 stick unsalted butter, softened, plus more for bowl and pan
1/2 cup heavy cream
2 large eggs, lightly beaten
1 1/2 teaspoons pure vanilla extract
1 cup packed dark-brown sugar
1/2 stick unsalted butter, melted and cooled
1/8 teaspoon salt
Dough: Pour milk into a small bowl. Sprinkle yeast evenly over milk, and let stand until foamy, 5 minutes. Stir together flour, granulated sugar, cinnamon, and salt in a medium bowl. Make a well in center, and add milk mixture, egg, and butter. Mix dough with your hands, and knead until dough comes together to form a ball. Place in a buttered bowl, and turn to coat. Cover with plastic wrap, and let rise in a warm place until doubled, about 2 hours.
Roll out dough to a 12-inch round on a lightly floured surface. Fit dough into a buttered 10-inch fluted tart pan with a removable bottom, and trim overhang flush with rim of pan. Cover with plastic wrap, and let rise in a warm place 15 minutes.
Filling: Preheat oven to 375 degrees. Stir together cream, eggs, and vanilla in a large bowl. Whisk in brown sugar, butter, and salt until smooth. Pour into tart shell, and bake 10 minutes. Reduce heat to 350 degrees, and bake until filling is set, about 20 minutes. Let cool in pan on a wire rack 10 minutes. Unmold, slide off bottom of tart pan, and let tart cool on rack. Serve warm or at room temperature.