Preheat the oven to 425°F. Prepare a muffin pan by either lining it with cupcake liners or spraying the tins with non-stick cooking spray. Set aside.

Make the streusel : In a small bowl, toss together the brown sugar, flour and cinnamon. Cut in the butter using a pastry knife or by mixing with a fork until the mix resembles coarse crumbs. Set it aside.

Start the muffins by beating the butter in a medium bowl using a hand held mixer or a stand mixer fitted with a paddle attachment. Beat for 1 minute, until smooth and creamy, then add the sugars and beat until all creamed together. Add the eggs, yogurt (or sour cream) and vanilla extract. Mix until completely combined. Scrape down the sides of the bowl as needed.

In a separate large bowl, whisk together the flour, baking soda, baking powder and salt. Then pour the wet ingredients into the dry and whisk together until combined and little lumps remain. Then use a wooden spoon or a rubber spatula to fold in the strawberries. The berries may bleed a little, creating a pink-ish batter.

Make the cheesecake filling by beating the cream cheese in a medium bowl using either a hand held mixer or a stand mixer fitted with a paddle attachment until creamy. Then, beat in the egg yolk, vanilla extract and sugar until combined.

Spoon about 1 tbsp. of muffin batter into the bottom of the muffin tins, then 1 spoonful of cheesecake batter, then more muffin batter, filling them up to the top. It's ok if some cheesecake mixture is showing through in some spots. Sprinkle each muffin with streusel and press it down gently so it sticks.

Bake the muffins for 5 minutes at 425°F, then, keeping the muffins in the oven, lower the temperature down to 350°F and bake for an additional about 16-18 minutes, or until a toothpick inserted into the center comes out clean.

Allow the muffins to cool for 10 minutes in the muffin pan, then transfer them to a wire rack to cool completely. Store covered in the fridge for up to 5 days. Muffins can also be frozen for up to 2 months. Just thaw in the fridge overnight.