Preheat oven to 350°F.
Combine butter and sugar in medium bowl.
Add eggs; mix well.
In a separate bowl, stir flour and pecans together; add to butter mixture until just moistened.
Fill greased and floured mini muffin cups. 2/3 full.
Bake at 350°F for 18 - 20 minutes.
Immediately remove cookies from pan; transfer to wire cooling racks.