1. Preheat oven to 350°.
2. To prepare cake, combine oil and vanilla bean in a small skillet over medium-high heat, and bring to a simmer. Remove from heat. Let stand 10 minutes or until mixture cools to room temperature. Scrape seeds from bean, and stir into oil; discard bean.
3. Combine oil mixture, 1 3/4 cups sugar, and 1/2 cup butter in a large bowl; beat with a mixer at medium speed until well blended (about 5 minutes). Add eggs, 1 at a time, beating well after each addition. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, and salt, stirring well with a whisk. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture.
4. Spoon batter into a 10-inch tube pan coated with baking spray, and spread evenly. Bake at 350° for 1 hour or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes on a wire rack, and remove from pan.
5. To prepare glaze, melt 1 tablespoon butter in a small skillet over medium heat; cook 2 minutes or until lightly browned. Remove from heat. Add next 3 ingredients (through vanilla), stirring until smooth. Drizzle glaze over warm cake.