For crust: In a small bowl, combine pecans, the 2 tablespoons brown sugar, and the melted butter. Press onto bottom of a 9-inch springform pan. Bake about 10 minutes or until nuts are toasted. Cool on a wire rack while preparing filling.
For filling: In a very large bowl, combine cream cheese, the 2 cups brown sugar, the flour, and vanilla. Beat with an electric mixer on medium speed until combined. Beat in bourbon until smooth. Using a wooden spoon, stir in eggs just until combined.
Pour filling into crust-lined pan; place in a shallow baking pan. Bake about 1 hour or until center appears nearly set when gently shaken. Cool in springform pan on wire rack 15 minutes. Using a small thin knife, loosen crust from side of pan. Cool 30 minutes more.
Remove side of pan. Cool 1 hour. Cover; chill at least 6 hours or up to 24 hours. Drizzle chocolate over cheesecake. Let stand a few minutes.