First, grease the muffin molds and refrigerate them or line them with paper molds.
Quarter the pears, remove the core and dice.
For the streusel mix flour, sugar and nuts, work with the butter to a crumbly mass. Refrigerate.
Meanwhile preheat the oven to 190 ° C top / bottom heat.
For the dough, stir the butter with the sugar until foamy, stir in the egg.
Mix the flour, baking powder and semolina, stir into the butter mixture with yogurt, milk and cinnamon. Finally fold in the pear pieces and the chopped nuts.
Fill into the prepared molds and sprinkle with the crumble.