1. PLACE the flour, sugar, ground pecans, baking powder and spices into a food processor and pulse to combine. Add the butter and process until the mixture resembles coarse breadcrumbs. Set aside 1 cup of mixture.
2. STIR together the sour cream and lemon juice, then add to the food processor along with the bicarbonate soda and eggs, and pulse until just combined. Spread half of the cake batter in the base of a greased and base lined 23cm round spring form pan. Sprinkle over a third of the reserved crumb mixture, and half of the chocolate chips and half of the pear. Spoon over the remaining cake batter. Top with remaining pears, chocolate chips, extra pecan nuts and remaining crumb mixture.
3. BAKE in a moderate oven 180°C for 50 minutes. Reduce the heat to 170°C and bake, shielding with foil if browning too much, for a further 30-40 minutes or until cooked when tested. Cool for 15 minutes in the pan before turning out onto a wire rack. Serve warm or cool completely and store in an airtight container until required.