1. Grease a large bowl with butter and set aside.
2. Place butter and milk into mixing bowl and heat 3 min/60°C (140°F)/speed 1.
Without a Thermomix, warm butter and milk gently in a small saucepan, stirring to combine.
3. Add yeast, sugar and egg and mix 10 sec/speed 3.
Without a Thermomix, transfer butter mixture to a bowl and stir with yeast, sugar and lightly whisked egg.
4. Add salt and flour and Knead/3 min.
Without a Thermomix, use a dough hook in a mixer to knead through flour and salt, or knead by hand until mixture is glossy, smooth and elastic.
5. Transfer dough into prepared bowl, cover with a kitchen towel and allow to rise in a warm place for 1 hour.
6. Preheat oven to 40°C (100°F) or lowest setting. Line a baking tray (30 x 40cm / 12-16 in) with baking paper and set aside. Divide dough into 2 portions and roll into thin logs (approx. 3cm (1.2 in) diameter). Form each log into a heart shape and interlink. Place onto prepared baking tray, sprinkle with walnuts and bake for 20 minutes.
7. Increase oven temperature to 190°C (375°F) and bake for a further 15 minutes or until bread is golden brown and sounds hollow when tapped. Serve warm or allow to cool completely before serving.