Cut the nectarines in half and remove the pits, then brush the cut sides with vegetable oil. Grill on a barbecue or in a grill pan cut side down over the highest heat. Cook until charred underneath, then flip and grill on the other side for 30 seconds.
Mix the ricotta, honey and vanilla extract together. Set aside.
Place the oats in a dry frying pan and toast over a high heat, stirring often, until they smell nutty. Add the butter, sugar and pecans to the pan and stir. Once the butter has melted, turn the heat down to medium-low and continue to cook the mixture for 2 minutes while stirring constantly. Decant into a bowl.
Serve the warm grilled nectarines with the ricotta mixture and a few tbsp of the pecan crumble.