Place your butter in a 9"x9" baking dish (a deep dish pie pan will work, but it will be VERY full!) and put the dish in the oven to melt the butter.
In a mixing bowl, combine eggs, Karo, ½ cup sugar, pecans and vanilla and mix well.
In another dish, mix remaining sugar, Bisquick, milk and cinnamon.
When the butter is melted, remove pan from oven and pour in Bisquick batter.
Next, gently spoon the pecan mixture over the batter, gently pouring in all the sugary goodness.
Bake for about 45 minutes, or until the cobbler wiggles a little bit, but isn't completely liquid on the inside. It will continue to set up as it cools.
Notes
It really needs at least an hour to set before you dip into it, but you will be rewarded for your patience. As I said before, this is great hot or cold. Think of it as upside down pecan pie!