For the sponge: Firstly, grease and line a 2lb loaf tin and set aside. Preheat the oven to 170C/150C Fan/Gas Mark 3.
In a large bowl, cream the butter and both sugars together until light and fluffy. Then add the eggs, one at a time, mixing well between each addition. Then in a small bowl, combine the flour and baking powder. Then mix this into the wet batter in two additions, mixing only until just combined.
Destone the peaches and chop into medium sized chunks, then mix this into the batter. Finally, add the leaves from 4 sprigs of thyme into the batter and mix to combine. Pour this into the prepared loaf tin, and set aside.
For the crumble/streusel: In a medium bowl, combine the butter, sugar and flour, rubbing between your fingers until it resembles breadcrumbs. Then sprinkle this liberally over the cake batter. Then place into the oven to bake for 1hr 15mins-1hr 20mins, until golden brown on the top and a knife inserted into the middle comes out clean. Leave to cool completely in the tin, then serve.
Loaf cake will keep in an air-tight container for 2-3 days.
Keyword brown sugar, cobbler, crumble, loaf cake, peach, streusel, thyme