Preheat the oven to 180ºC, fan 160ºC, gas 4.
Put the butter, sugar, eggs and flour in a bowl and, using an electric hand mixer, beat until thoroughly combined. Stir in the orange zest and juice, and the yogurt.
Spoon the mixture into either a deep 20cm cake tin, lightly greased and lined with baking parchment, or a 12-hole muffin tin lined with paper muffin cases. Bake the cake for 50-55 minutes (the muffins for 25-30 minutes) until risen and golden and a skewer inserted into the middle comes out clean. Cool in the tin for 10 minutes, then turn out, remove the paper and cool completely on a wire rack.
While the cake is cooling, make the decorations. Bring a pan of water to the boil, add the sliced zest and boil for 1 minute until the zest starts to soften. Dry on kitchen paper. Once the cake has cooled, dust with icing sugar and decorate with the strips of orange zest.
Cook's tip: To freeze, cool, then wrap in a freezer bag and freeze for up to 3 months.