Preheat the oven to 200ºC/180ºC fan/gas 6. In a pan, melt the butter and oil together before adding the sliced onion. Fry over a medium heat for approximately 5 minutes until the onions have softened but not coloured.
Add the garlic and mixed herbs and fry for a further 1 minute before removing from the heat and allowing to cool fully.
In a large bowl, combine the cornmeal, flour, baking powder, salt and sugar. In a separate bowl, crack in the eggs and, using a balloon whisk, whisk for 1-2 minutes until light and fluffy. Gently add the buttermilk and milk to the eggs, continually whisking.
Pour the buttermilk mixture into the dry ingredients and fold together. Sprinkle in half the Cheddar and the chilli flakes and continue to fold until all the ingredients are well combined and a thick batter is formed.
Line a deep baking tray or dish (we used a 25x22cm baking tin) with greaseproof paper. Pour the batter into the tin and level the surface with the back of a spoon. Sprinkle with the remaining Cheddar.
Place the tin in the oven and bake for 30-35 minutes until it has risen slightly, the top is golden and crispy, and an inserted skewer is clean when removed from the centre of the loaf. Allow to cool slightly for 5 minutes.
Serve either warm or allow to fully cool and serve at room temperature. Scatter with more chilli flakes for extra heat, some sliced spring onions and a bowl of sour cream.
