*The recipe works well with white flour, spelt flour, or all purpose gluten free flour.
1. Line a muffin tin with paper liners, or grease well. Set aside.
2. Let cream cheese come to room temperature, then blend all cream cheese filling ingredients in a small food processor or with hand beaters until smooth.
3. Next, make the crumble topping by stirring all streusel ingredients except butter in a mixing bowl. Cut in the butter or softened oil with a pastry cutter or fork to form small crumbles.
4. Preheat the oven to 350° Fahrenheit or 176° Celsius.
5. Whisk water, lemon juice and zest, optional egg, remaining vanilla extract, and remaining butter (melted) or oil in a large mixing bowl. Stir in the remaining flour, sugar, baking powder, and salt just until evenly mixed.
6. Spoon about two tablespoons muffin batter into the bottom of each lined or greased tin.
7. Add a spoonful of cream cheese filling, then divide the rest of the muffin batter on top.
8. Sprinkle the oat streusel topping over the unbaked muffins. Bake on the oven's center rack for 22 minutes or until a toothpick inserted into the center of a muffin comes out mostly clean.
9. Enjoy hot from the oven. Or let cool before loosely covering with a towel and storing at room temperature overnight or completely covered in the refrigerator for up to five days. You can also freeze leftover lemon cream cheese muffins for up to two months.