Cake: Preheat an oven to 165 degrees C. Combine flour, baking powder, baking soda and salt in a bowl. Set aside. Grease and flour a ring tin.
Beat butter, brown sugar and white sugar with an electric mixer in a large bowl until light and fluffy. The mixture should be noticeably lighter in colour. Add the bananas, followed by the eggs one at a time, allowing each egg to blend into the butter mixture before adding the next. Beat in 2 teaspoons of vanilla with the last egg. Pour in the flour mixture alternately with the milk, mixing until just incorporated. Fold in the pecans; mixing just enough to evenly combine. Pour the batter into prepared tin.
Bake in the preheated oven until a toothpick inserted into the centre comes out clean; about 1 hour and 20 minutes.
Glaze: Heat butter, brown sugar, white sugar, vanilla and cream in a saucepan over medium heat. Stir continuously until the sugars have dissolved then gently simmer for 1 minute. Pour over baked cake while still in the tin. Cool in the tin for 10 minutes before removing to cool completely on a wire rack.