Preheat the oven to 350°F (180°C). Line the compartments of a muffin pan with paper liners (or spray with cooking spray).
Topping: In a medium bowl, combine the canola oil or melted tub margarine, SPLENDA® Brown Sugar Blend, flour, rolled oats and ground cinnamon for the topping. Mix until crumbly and set aside.
Batter: In a large bowl or a food processor fitted with the steel blade, combine the SPLENDA® Granulated, oil, egg, and vanilla extract. Mix well or process for 1 minute, until well blended. Combine the flours, baking soda, baking powder, cinnamon and salt in a bowl. Add to the SPLENDA® mixture along with the yogurt and mix just until combined (or process with quick on/off pulses, just until combined). Stir in the apples with a rubber spatula.
Scoop the batter into the prepared muffin pan, filling each compartment about two thirds full. Sprinkle evenly with reserved topping.
Bake at 350°F (180°C) for 22 to 25 minutes or until golden brown and the tops spring back when lightly touched.