FundraiserFactory.sol

...
event FundraiserCreated(Fundraiser indexed fundraiser, address indexed owner);

function createFundraiser(
    string memory name,
    string memory image,
    string memory description,
    uint256 goalAmount,
    address payable beneficiary
  ) public {
    Fundraiser fundraiser = new Fundraiser(
      name,
      image,
      description,
      goalAmount,
      beneficiary,
      msg.sender
    );
    _fundraisers.push(fundraiser);
    emit FundraiserCreated(fundraiser, msg.sender);
  }
  ...