In large bowl, mix 1/2 cup of the flour, the sugar, and yeast.
Add 1/2 cup of warm water and let stand until foamy
Add milk, salt, 1 1/2 cups of the flour, vanilla, butter and egg.
Beat on low speed one minute, scraping bowl often.
Beat on medium speed for 1 minute more.
Stir in remaining flour, one cup at a time until you have a soft dough that is easy to handle.
On a lightly floured surface knead the dough about five minutes or until smooth and elastic.
Place in a greased bowl that is twice the size of the ball of dough; turn to coat all sides of the dough.
Cover and let rise in a warm place for about 1 1/2 hours or until double and an indentation remains when you poke it with your finger.
Grease a 13 x 9 inch pan.
Heat 1 cup of brown sugar and 1/2 cup of butter to a boil, stirring constantly.
Remove from heat.
Stir in corn syrup and cool for a few minutes.
Pour into the bottom of the greased 13 x 9 inch pan and sprinkle with pecan halves.
Mix 1 chopped pecans, bacon,1/2 cup brown sugar, and cinnamon together.
Mix melted butter and bacon grease.
Punch dough down.
On a floured surface roll out the dough into a 12 x 10 inch rectangle.
Spread melted butter mixture over dough.
Sprinkle with the pecan mixture.
Roll up tightly and pinch long edge of the dough to seal.
Cut in 12 slices and lay cut side down over the pecan-caramel mixture in the pan.
Cover tightly and place in the refrigerator for 12 to 24 hours.
Heat oven to 350F
Uncover rolls and bake for 30 minutes, or until tops are golden brown.
Remove from oven and turn out onto a heat proof plate.
Let pan remain over the rolls for a minute or two to ensure all of the caramel drizzles onto the rolls.