Spinach potato soup with savoury egg custard

Savoury egg custard

• 4 eggs
• 100 g whole milk
• ½ tsp salt
• 1 - 2 pinches ground nutmeg

Spinach potato soup

• 80 g onions, cut in halves
• 20 g oil
• 40 g celeriac
• 100 g carrots, cut in pieces (2 cm)
• 200 - 250 g potatoes, cut in pieces (2 cm)
• 80 g leeks, cut in slices (1 cm)
• 800 g water
• 1 heaped tsp vegetable stock paste, homemade,
  of 1 vegetable stock cube (for 0.5 l)
• ¼ tsp ground nutmeg
• 1 tsp salt, plus extra to taste
• ¼ tsp ground pepper, plus extra to taste
• 250 g fresh spinach leaves
  of 250 g frozen spinach leaves, defrosted
• 80 g cream, 30% fat