Pecan crumble pineapple cake

Pecan crumble:

3/4 c (180 ml) chopped pecans

1/3 c (80 ml) quick cook oats

1/3 c (80 ml) brown sugar

2 tbsp (30 ml) unbleached all-purpose flour

2 tsp (5 ml) ground cinnamon

2 tbsp (30 ml) melted butter

Cake:

2 c (500 ml) unbleached all-purpose flour

1 1/2 tsp (7 ml) baking powder

1/2 tsp (2 ml) baking soda

1 pinch of salt

3/4 c (180 ml) softened butter

1 c (250 ml) brown sugar

3 eggs

1/2 tsp (2 ml) pure vanilla extract

1/4 c (60 ml) sour cream

1 can 14 oz (398 ml) Del Monte pineapple chunks