Preheat oven to 350 degrees F. For crust, in a medium bowl combine finely crushed chocolate cookies and the 3 tablespoons sugar. Stir in the melted butter. Press chocolate mixture onto the bottom of a 9-inch tart pan with a removable bottom. (Use the bottom of a 1/2-cup dry measuring cup to press the chocolate cookie mixture evenly into the pan.) Bake about 10 minutes or until set. Cool on a wire rack.
For filling, in a medium saucepan whisk together half-and-half, flour, and salt. Cook over medium heat until simmering, stirring frequently. In a medium bowl whisk together egg yolks and the 1/3 cup sugar. Gradually whisk hot half-and-half mixture into egg yolk mixture. Return egg yolk mixture to saucepan. Cook and stir over medium heat until mixture is thickened and bubbly. Remove from heat. Add peanut butter and vanilla, whisking until combined. Pour filling into crust, spreading evenly. Cover and chill for 3 hours.
For chocolate glaze, in a heavy small saucepan combine chopped chocolate and the 5 tablespoons butter. Cook and stir over low heat until melted. Remove from heat. Stir in corn syrup; cool for 10 minutes.
Pour chocolate glaze over filling; lift and tilt pan so glaze flows evenly over tart. Cover and chill for at least 1 hour or up to 24 hours.
Let stand at room temperature for 10 minutes before serving. Using a small sharp knife, gently loosen edges of tart from sides of pan; remove sides of pan. To cut, dip a sharp knife into hot water; dry the knife. Quickly score top of the tart with the warm knife. Cut tart along score marks.