Prepare the Cake: Preheat oven to 325°F. Sift together flour and salt. Beat butter, sugar, and vanilla on medium speed with an electric mixer until light and fluffy, 3 to 5 minutes. Add eggs, 1 at a time, beating on low speed until blended after each addition. Gradually add flour mixture, beating on low speed just until blended and smooth (do not over mix). Pour the batter into a greased (with shortening) and floured 9- x 5-inch loaf pan; smooth top.

Bake in preheated oven until a wooden pick inserted in center comes out clean, about 1 hour 15 minutes. Cool in pan on a wire rack 15 minutes. Remove from pan to wire rack; cool completely, about 1 hour.

Prepare the Glaze: Bring cream just to a simmer in small saucepan over medium heat; pour hot cream over chopped chocolate in a medium bowl. Let stand 2 minutes; whisk until smooth. Place a piece of plastic wrap directly on surface of mixture; let stand at room temperature until firm, about 2 hours.

Prepare the Filling: Combine caramel candies and cream in a small saucepan; cook over low heat, stirring constantly, until melted and smooth, about 4 minutes. Remove from heat, transfer to a bowl, and refrigerate, uncovered, until slightly thickened but still spreadable, 10 to 15 minutes.

Meanwhile, assemble Cake: Use a serrated knife to cut the cake horizontally into 3 layers. Place 1 layer on a serving plate; spread with half of Filling. Top with second layer; spread with remaining Filling. Top with third layer. Cover with plastic wrap and let stand at room temperature until filling is set, about 1 hour.

Spread Glaze over top and sides of cake. Garnish with candy bars as desired.