1. Preheat oven to 350º, with rack in center. On a lightly floured surface, roll out pie dough to a 12-inch round, about 1/8 inch thick. Wrap dough around rolling pin, and unwrap over 9-inch tart pan with a removable bottom.. Press dough into bottom and up sides of pan; trim edge of dough.

2. In a large bowl, whisk together eggs, sugar, light corn syrup, 4 tsp melted unsalted butter, and vanilla. Scatter chocolate evenly over tart shell. Pour filling over chocolate. Arrange pecans on top. Dot with 2 tsp chilled butter.

3. Place tart pan on rimmed baking sheet. Bake until filling is set, 45 to 60 minutes. If pecans are browning too quickly, tent pan with foil. Remove from oven; while still hot, drizzle with bourbon, if desired. Let tart cool completely.

4. Before serving, in bowl of a standing mixer, whisk heavy cream, sour cream, brown sugar and salt until combined. Cover with plastic wrap and refrigerate at least four hours (or up to 24 hrs) stirring occasionally to ensure that the sugar dissolves.

5. When ready to serve, add bourbon and beat mixture at medium speed until small bubbles form around edges, about 40 seconds. increase speed to high and beat until fluffy, about 1 minute longer. Serve immediately.