Split Pea & Ham Soup with Ham-Cheddar Jaffles

Ingredients

• 40 gm butter, coarsely chopped
• 2 onions, finely chopped
• 1 fennel bulb, finely chopped
• 4 garlic cloves, finely chopped
• 1 ham hock (about 1.2kg)
• 500 gm dried green split peas (2¼ cups)
• 360 gm frozen baby green peas (3 cups)
• 1 cup baby spinach (firmly packed)
• ½ cup mint, plus extra to serve (firmly packed)
• ½ cup flat-leaf parsley (firmly packed)
• Finely grated rind and juice of ½ lemon, or to taste
• Softened butter, for spreading
• 8 slices soft white bread
• Dijon mustard, to taste
• 60 gm coarsely grated vintage Cheddar (½ cup)