Pâté Chinois (Canadian Shepherd's Pie)

Filling

• 30 g olive oil, divided
• 150 g onion, divided
• 2 garlic cloves, divided
• 500 g lean ground beef, crumbled into small portions, divided
• 1 tsp salt, divided, plus extra to season, to taste
• ¼ tsp freshly ground black pepper, divided, plus extra to season, to taste
• 25 g fresh parsley or ½ bunch, patted dry, cut in thirds
• 2 tsp ground paprika
• 1 tbsp Worcestershire sauce
• 398 ml canned sweet corn kernels, drained (approx. 1 can)
  of 398 ml canned creamed sweet corn, undrained (approx. 1 can)
• 995 g water
• 60 g vinegar

Topping

• 700 g yellow potatoes, sliced or diced (2.5 cm/(½ in.)
  of 700 g Yukon gold potatoes, sliced or diced (2.5 cm/(½ in.)
• 175 g whole milk
• 60 g butter, diced, divided, to taste
• 1 tsp salt
• 1 tsp dried ground savory