Preheat the oven to 180*C and line a muffin tray with cases.
Mix the yoghurt and sugar for the dough together until smooth. Sift in the flour, sprinkle in the salt and stir to form a dough. Form a small ball shape and transfer onto a lightly floured work surface.
Equally divide the dough into 8 pieces and then divide each piece again into 5-6 pieces. Use your hands to roll the small pieces into ball shapes.
Melt the butter and peanut butter in a small saucepan, stir to combine.
Dip each ball in the melted butter mixture then roll the ball in the sugar mixture to coat. Place the balls into a muffin case and repeat for 5-6 balls per muffin case. Repeat to form 8 muffins.
If you have any buttery mixture left, pour it over the muffins and sprinkle with more sugar.
Bake until nicely risen and baked through (around 21 minutes) and then carefully remove from the muffin tin from the oven. Place on a wire rack to cool.
Make the glaze by stirring all the ingredients together. Pour over the muffins and enjoy hot or cool.
Once cool, store in a sealed container for 1-2 days at room temperature.