Preheat your oven to 425 °F.
Grease 14 cupsof 2muffin pans with cookingspray.
or crumb topping: in a medium bowl, blendtogether the sugars and cinnamon.
Add in the melted butterand with a fork,gently stir to blend.
Add in the flour and with a fork, gently stiruntil a crumbly mixture forms.
Set aside.
For muffins: in a bowl, add the flour, baking powder,baking soda, cinnamon and salt andwith a wire whisk, mix well.
In the bowl of a handheld mixer, fitted witha paddle attachment, add the butter and both sugars and mix on high speed untilsmooth and creamy.
Add the yogurt, eggs and vanilla extract andbeat on medium speed for about 1 minute.
Then increase the speed of mixer to high andmixuntil wellblended.
While the mixer running on low speed, add theflour mixture and milk and beat until just blended.
Fold in the apple pieces.
Place the mixture into prepared muffincups evenly.
Top each muffin with crumb topping and gentlypress down.
Bake for about 5 minutes.
Immediately set the temperature of oven to 350°F and bake for about 15-18 minutes.
Remove the muffin pans from oven and placeonto a wire rack to cool for about 10 minutes.
Then invert the muffins onto the wire rack tocool before serving.