FOR CRUST: Combine crumbs and butter in large bowl and mix well. Press evenly into bottom of 9" springform pan.
FOR FILLING: Preheat oven to 350°. Blend cheese and 1 1/4 c. brown sugar in large bowl until smooth. Add eggs, one at a time, beating well after each addition. Stir in chopped pecans, flour and vanilla and mix thoroughly. Pour into pan, spreading evenly.
Bake until set, 50-55 minutes. Let cheesecake cool to room temperature, then cover and refrigerate overnight.
FOR TOPPING: Combine brown sugar and butter in small saucepan. Place over low heat and cook, stirring occasionally until smooth and thickened, about 5 minutes
Pour hot topping over chilled cake, spreading to cover top. Remove springform pan. Arrange pecan halves decoratively around edge of topping. Serve slightly chilled or at room temperature.