Combine egg yolk, lemon juice and yoghurt in a heatproof bowl. Place bowl over a saucepan of water, ensuring base of bowl is not touching water. Bring water to a gentle simmer. Cook, whisking, for 5-8 minutes or until thickened. Whisk mustard until combined.
Meanwhile, heat a small non-stick frying pan over medium-high heat. Cook bacon for 2 minutes each side until crisp.
Place Egg Poacher insert into omelette maker. Crack one egg into each cup. Close and microwave on medium (70%) for 50-60 seconds, or longer for firm poached eggs. Carefully spoon out eggs.
Top toast with bacon, eggs, hollandaise and chives. Season with salt and pepper and serve.